simplified middle school chemistry class 10 answers

New Simplified Chemistry Class 10 ICSE Solutions – Practical Chemistry

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These Solutions are part of New Simplified Middle School Chemistry Class 10 ICSE Solutions Here we have given New Simplified Chemistry Class 10 ICSE Solutions – Practical Chemistry

2003

Question 1.
State the colour of the residue obtained on cooling when the following carbonates are heated :

1. zinc carbonate
2. lead carbonate
3. copper carbonate.

Answer:

1. In case of zinc carbonate, residue is yellow when hot and White when cold
   
2. In case of lead carbonate, residue is reddish-brown when hot and yellow when cold
   
3. In case of Copper carbonate, residue is black when cold.
   

2004

Question 1.
Sodium hydroxide solution is added first in a small quantity, then in excess to the aqueous salt solutions of copper (II) sulphate, zinc nitrate, lead nitrate, calciumchloride and iron (III) sulphate. For each of the aqueous salt solutions, state —

(a) the colour of the precipitate when NaOH is added in a small quantity ;
(b) the nature of precipitate (i.e. soluble or insoluble) when NaOH is added in excess.

Answer:

2005

Question 1.
The questions below refer to the following salt solutions listed A to F : A : Copper nitrate B : Iron (II) sulphate C : Iron (HI) chloride D : Lead nitrate E : Magnesium sulphate F : Zinc chloride.

1. Which two solutions will give a white precipitate when treated with dilute hydrochloric acid followed by barium chloride solution, (i.e. white ppt. insoluble in dil. HCl)
2. Which two solutions will give a white ppt. when treated with dil. HNO₃ and AgNO₃ soln.
3. Which soln. will give a white ppt. when either dil. HCl or dil. H₂SO₄ is added to it.
4. Which soin. becomes a deep/inky blue colour when excess of ammonium hydroxide is added to it.
5. Which solution gives a white precipitate with excess ammonium hydroxide solution.

Answer:

1. B and E [Iron(II) Sulphate and Magnesium sulphate]
2. C and F [Iron(II) chloride and Zinc chloride]
3. D [Lead nitrate]
4. A [Copper nitrate]
5. D [Lead nitrate]

2006

Question 1.
From the list of substances given—Ammonium sulphate, Lead carbonate, Chlorine, Copper nitrate, Ferrous sulphate — State : A substance that turns moist starch iodide paper blue.
Answer:
Chlorine

Question 2.
State what is observed when excess of ammonia passed through an aqueous solution of lead nitrate.
Answer:
When ammonia is passed through an aq. solution of lead nitrate, chalky white precipitate of lead hydroxide is formed which is insoluble in excess of ammonia.

Question 3.
Give one test each to distinguish between the following pairs of chemicals solutions

1. Zn(NO₃)₂ and Ca(NO₃)₂
2. NaNO₃ and NaCI
3. Iron [III] chloride and copper chloride.

Answer:

1. Add NaOH solution in excess to the two solutions. The one in which white ppt. initially formed dissolves in excess of NaOH solution is Zn(NO₃)₂ solution and the other is Ca(NO₃)₂ solution.
2. Add freshly prepared ferrous sulphate solution to the two solutions. Then by the side of the test tube, pour cone, sulphuric acid (H₂SO₄) to each slowly. The one in which brown ring appears is sodium nitrate solution while the other is sodium chloride sol.
3. Add NaOH solution to both the solutions. The one which give a reddish brown ppt. is Iron(II) chloride solution and the one which gives blue ppt. is copper chloride solution.

Question 4.
Give a reason why carbon dioxide and sulphur dioxide cannot be distinguished by using lime water.
Answer:
Because both turns lime water milky.

2007

Question 1.
Salts A, B, C, D and E undergo reaction (i) to (v) respectively. Identify the anion present in these salts on the basis of these reactions.

1. When AgNO₃ solution is added to a soln. of A, a white precipitate, insoluble in dilute nitric acid, is formed.
2. Addition of dil. HCl to B produces a gas which turns lead acetate paper black.
3. When a freshly prepared solution of FeSO₄ is added to a soln. of C and cone. H₂SO₄ is gently poured from the side of the test-tube, a brown ring is formed.
4. When dil. H₂SO₄ is added to D a gas is produced which turns acidified K₂Cr₂O₇ soln. from orange to green.
5. Addition of dil. HCI to E produced an effervescence. The gas produced turns limewater milky but does not effect acidified K₂Cr₂O₇ soln.

Answer:

1. Chloride Cl^1-
2. Sulphide S^2-
3. Nitrate NO₃^2-
4. Sulphite SO₃^2-
5. Carbonate CO₃^2-

Question 2.
How will the addition of barium chloride soln. help to distinguish between dil. HCl and dil. H₂SO₄.
Answer:
Barium chloride does not react with dil HCl but with dil H₂SO₄ gives a white ppt. of barium sulphate.

2008

Question 1.
The salt which, in solution gives a pale green ppt. with sodium hydroxide solution and a white precipitate with barium chloride solution is :

A : Iron (III) sulphate
B : Iron (II) sulphate
C : Iron (II) chloride
D : Iron (III) chloride

Answer:

B : Iron (II) sulphate

2009

Question 1.
Carbon dioxide and sulphur dioxide gas can be distinguished by using :

(A) Moist blue litmus paper
(B) Lime water
(C) Acidified potassium dichromate paper
(D) None of the above.

Answer:

(C) Acidified potassium dichromate paper

Question 2.
Identity the substances ‘R’ based on the information given below :
The pale green solid ‘R’ turns reddish brown on heating. Its aqueous solution gives a white precipitate with barium chloride solution. The precipitate is insoluble in mineral acids.
Answer:
Ferrous sulphate (Fe₂SO₄).

Question 3.
Give one chemical test to distinguish between the following pairs of compounds.

1. ZnSO₄ and ZnCl₂
2. FeCl₂ and FeCl₃
3. Calcium nitrate soln. and Calcium chloride soln.

Answer:

2010

Question 1.
Select the correct answer from A, B, C, D and E –

(A) Nitroso Iron (II) sulphate
(B) Iron (III) chloride
(C) Chromium sulphate
(D) Lead (II) chloride
(E) Sodium chloride.

The compound which is responsible for the green colour formed when SO₂ is bubbled through acidified potassium dichromate solution.
Answer:

(C) Chromium sulphate

Question 2.
State your observation –

1. A piece of moist blue litmus paper
2. Paper soaked in potassium permanganate solution- is introduced into a gas jar of sulphur dioxide.

Answer:

1. Moist blue litmus turns red and finally colourless as SO₂ act as an acidic gas and then a bleaching agent.
2. The pink colour of potassium permanganate paper turns colourless because of bleaching property of sulphur dioxide.

Question 3.
Write the equation for the reaction of magnesium sulphate solution with barium chloride solution.
Answer:
MgSO₄ + BaCl₂ → BaSO₄ + MgCl₂

2011

Question 1.
Choose from the list of substances – Acetylence gas, aqua fortis, coke, brass, barium chloride, bronze, platinum.
An aqueous salt solution used for testing sulphate radical.
Answer:
Barium chloride.

2012

Question 1.
Name the gas which turns acidified potassium dichromate clear green.
Answer:
Sulphur dioxide gas (SO_s)

Question 2.
Identify the anion present in the following compounds :

1. Compound X on heating with copper turnings and concentrated sulphuric acid liberates a reddish brown gas.
2. When a solution of compound Y is treated with silver nitrate solution a white precipitate is obtained which is soluble in excess of ammonium hydroxide solution.
3. Compound Z which on reacting with dilute sulphuric acid liberates a gas which turns lime waer milky, but the gas has no effect on acidified potassium dichromate solution.
4. Compound L on reacting with Barium chloride solution gives a white precipitate insoluble in dilute hydrochloric acid or dilute nitric acid.

Answer:

1. Nitrate ion, NO₃^–
   
2. Chloride ion, Cl^–
   
3. Carbonate ion, CO₃^2-
   
4. Sulphate ion, SO₄^2-
   

Question 3.
State one chemical test between each of the following pairs :

1. Sodium carbonate and Sodium sulphite
2. Ferrous nitrate and Lead nitrate
3. Manganese dioxide and Copper(II) oxide

Answer:

1. Treat each of the compound with dilute sulphuric acid. In case of sodium carbonate a colourless and odourless gas is evolved. In case of sodium sulphite a colourless gas evolved which has a choking smell and causes coughing.
2. To each of the aqueous solutions of compounds add aqueous sodium hydroxide solution. A dirty green precipitate is formed in case of ferrous nitrate, whereas a white chalky precipitate is formed in case of lead nitrate.
3. Heat each of the compound with cone, hydrochloric acid. In case of manganese dioxide a greenish yellow gas (chlorine) is evolved. In case of copper(II) oxide, no gas evolved and a bluish green solution is formed.

Question 4.
State one observation : A zinc granule is added to copper sulphate solution.
Answer:
The blue colour of copper sulphate solution fades to form a colourless solution.

Question 5.
Give balanced equation for the reaction :
Silver nitrate solution and Sodium chloride solution.
Answer:

2013

Question 1.
Give a chemical test to distinguish between :

1. NaCl soln. and NaNO₃ soln.
2. HCl gas and H₂S gas.
3. Calcium nitrate soln. and zinc nitrate soln.
4. Carbon dioxide gas and sulphur dioxide gas.

Answer:

1. Add silver nitrate solution to sodium chloride solution and sodium nitrate solution. In case of sodium chloride, a curdy white ppt. is formed. In case of sodium nitrate solution the reaction mixture remains colourless.
2. Moist lead acetate paper turns black in case of hydrogen sulphide gas, but does not change its colour in case of hydrogen chloride gas.
3. To each of the solution add first sodium hydroxide solution in small amount and then in excess. In case of calcium y nitrate a fine white precipitate is formed, which does not dissolve in excess of sodium hydroxide. In case of zinc nitrate a gelatin like white precipitate is formed which dissolves in excess of sodium hydroxide.
4. To each of the gas add few drops of acidified potassium dichromate solution. In case of carbon dioxide no change takes place. In case of sulphur dioxide, potassium dichromate solution turns blue.

Question 2.
From A : CO ; B : CO₂ ; C : NO₂ ; D : SO₃ – State which will not produce an acid on reaction with water.
Answer:
A : CO

2014

Question 1.
Distinguish between : Sodium nitrate and sodium sulphite (using dilute sulphuric acid)
Answer:
Sodium nitrate will not react with dilute sulphuric acid.
Sodium sulphite reacts with dil. sulphuric acid to liberate foul smelling hydrogen sulphide gas.

Question 2.
State your observation : When moist starch iodide paper is introduced into chlorine gas.
Answer:
The starch iodide paper turns blue due to the liberation of free iodine.

Question 3.
The flame test with a salt P gave a brick red flame. What is the cation in P?
Answer:
Cation in P is Ca²⁺ (calcium ion).

Question 4.
Gas Q turns moist lead acetate paper silvery black. Identify the gas Q.
pH of liquid R is 10. What kind of substance is R?
Answer:
The gas Q is H₂S (Hydrogen sulphide).
The substance R is a alkaline.

2015

Question 1.
Select the gas that has a charateristic rotten egg smell. [ammonia, ethane, hydrogen chloride, hydrogen sulphide, ethyne]
Answer:
Hydrogen sulphide

Question 2.
State one relevant observation : When hydrogen sulphide gas is passed through lead acetate solution.
Answer:
When hydrogen sulphide gas is passed through lead acetate solution, it forms a black precipitate of lead sulphide.

Question 3.
Identify the anion present in each of the following compounds: A, B, C :

1. Salt ‘A’ reacts with cone. H₂SO₄ producing gas which fumes in moist air and gives dense fumes with ammonia.
2. Salt ‘B’ reacts with dil. H₂SO₄ producing a gas which turns lime water milky but has no effect on acidified potassium dichromate solution.
3. When barium chloride solution is added to salt solution. ‘C’ a white precipitate insoluble in dilute hydrochloric acid is obtained.

Answer:

1. Chloride ion (Cl^–)
2. Carbonate ion (CO₃²) or bicarbonate ion (HCO₃^-1)
3. Sulphate ion (SO₄^2-)

Question 4.
Identify the cation present in each of the following compounds — W, X, Y, Z :

1. To solution ‘W’, ammonium hydroxide is added in minimum quantity first and then in excess. A dirty white precipitate is formed which dissolves in excess to form a clear solution.
2. To solution ‘X’ ammonium hydroxide is added in minimum quantity first and then in excess. A pale blue precipitate is formed which dissolves in excess to form a clear inky blue solution.
3. To solution ‘Y’ a small amount of sodium hydroxide is added slowly and then in excess. A white insoluble precipitate is formed.
4. To a salt ‘Z’ calcium hydroxide solution is added and then the mixture is heated. A pungent smelling gas turning moist red litmus paper blue is obtained.

Answer:

1. Zn²⁺ (Zinc Ion)
2. Cu²⁺ (Copper (II) Ion)
3. Ca²⁺ (Calcium Ion)
4. NH₄⁺ (Ammonium Ion)

2016

Question 1.
Identify the cations in each of the following cases :

1. NaOH solution when added to the solution ‘A’ gives a reddish brown precipitate.
2. NH₄OH solution when added to the solution ‘B’ gives white ppt which does not dissolve in excess.
3. NaOH solution when added to the solution ‘C’ gives white ppt which is insoluble in excess.

Answer:

1. Ferric (Fe³⁺) ion
2. Plumbous (Pb²⁺) ion
3. Calcium (Ca²⁺) ion

2017

Question 1.
Choose the correct answer from the options – A chloride which forms a precipitate that is soluble in excess of ammonium hydroxide, is :

A. Calcium chloride
B. Ferrous chloride
C. Ferric chloride
D. Copper chloride.

Answer:

D. Copper chloride.

Question 2.
Identify the substance underlined – Cation that does not form a precipitate with ammonium hydroxide but forms one with sodium hydroxide.
Answer:
Magnesium ions.

Question 3.
Identify the salts P and Q from the observations given below :

1. On performing the flame test salt P produces a lilac coloured flame and its solution gives a white precipitate with silver nitrate solution, which is soluble in ammonium hydroxide solution.
2. When dilute HCl is added to a salt Q, a brisk effervescence is produced and the gas turns lime water milky. When NH₄OH solution is added to the above mixture [after adding dilute HCl], it produces a white precipitate which is soluble in excess NH₄OH solution.

Answer:

(i) The salt P is potassium chloride.

• Reason : K⁺ ions give lilac colour to flame and Cl^– ions react with silver nitrate to form silver chloride precipitate which is soluble in excess of ammonium hydroxide.

(ii) The salt Q is zinc carbonate.

• Reason : CO₃^-2 ions are responsible for the liberation of carbon dioxide with HCl. The salt formed is zinc chloride which forms white precipitate with ammonium hydroxide. This precipitate is soluble in excess of ammonium hydroxide.

Additional Questions

Question 1.
The following materials are provided – solutions of cobalt chloride, ammonia, potassium permanganate, lime water, starch-iodide, sodium hydroxide, lead acetate, potassium iodide. Also provided are litmus and filter papers, glowing splinters and glass rods. Using the above how would you distinguish between :

(a) a neutral, acidic and a basic gas
(b) oxygen and hydrogen gas
(c) carbon dioxide and sulphur dioxide gas
(d) chlorine and hydrogen chloride gas
(e) hydrogen sulphide and nitrogen dioxide gas
(f) ammonia and carbon dioxide gas
(g) zinc carbonate and potassium nitrate
(h) hydrated copper sulphate and anhydrous copper sulphate
(i) ammonium sulphate and sodium sulphate.

Answer:

(a) Neutral gas does not effect litmus paper. Acidic gas turns blue litmus paper red and basic gas turns red litmus blue.
(b) Oxygen is obtained by heating KMNO₄ whereas hydrogen gas is obtained with the action of Zn and dil H₂SO₄.
(c) No effect of CO₂ on KMnO₄ or K₂Cr₂O₇ whereas SO₂ turns K₂Cr₂O₇ from orange to green.
(d) Chlorine decolourises the colouring matter whereas HCl does not.
(e) H₂S gas turns KMnO₄ from pink to colourless and NO₂ liberates violet vapours with KI.
(f) NH₃ turns red litmus blue and S02 turns blue litmus red.
(g) Lime water turns zinc carbonate milky and no effect on potassium nitrate.
(h) Hydrated copper sulphate anhydrous copper sulphate. Take some dry CuSO₄ on filter paper. It will be white in colour.
anhydrous copper sulphate white in colour. CuSO₄ (white powder)
Now keep it in air for some time, it will absorb water vapous from atmosphers, its colour will change to blue.
(i) Ammonium sulphate and sodium sulphate : When ammonium sulphate is heated with NaOH, gas ammonia is producedwhich turns red litmus blue. But sodium sulphate has no reaction with NaOH.

Question 2.
Give a chemical test to distinguish between the following:

1. Sodium carbonate and sodium sulphate
2. Potassium chloride and potassium nitrate
3. Copper carbonate and copper sulphite
4. Lead chloride and lead sulphide
5. Iron (II) sulphate and iron (III) sulphate
6. Calcium sulphate and zinc sulphate
7. Lead nitrate and zinc nitrate
8. Copper sulphate and calcium sulphate
9. Manganese dioxide and copper (II) oxide
10. dil. HCl, dil. HNO₃, dil. H₂SO₄.

[explain the procedure for the preparation of the solutions for the above tests wherever required]
Answer:
(i) Sodium carbonate and sodium sulphate : Add BaCl₂ solution to Na₂CO₃,a white precipitates produced which are soluble in dil. HCl.

(ii) Add cone. H₂SO₄ to potassium chloride and heat.
colourless gas produced which gives dense-white fumes when a glass rod dipped in ammonia is brought near it.
To the salt solution potassium nitrate, add cone. H₂SO₄ and copper turnings and heat.
Reddish brown fumes evolved which gives violvet vapours and turns potassium iodide paper brown.
(iii) On adding dilute H₂SO₄ to copper carbonate acid heating, a colorless odour less gas is evolved which turns lime water milky and has no effect on KMnO₄ or K₂Cr₂O₇ solution.

CO₂ gas turns lime water milky.
Now add dil. H₂SO₄ to copper sulphite and heat.
A colourless gas with suffocating odour evolved which turns lime water milky and changes then pink colour of acidified KMnO₄ to colourless and orange colour of acidified K₂Cr₂O₇ to clear green.
(iv) Added MnO₂ and cone. H₂SO₄ to the salt Lead Chloride and heat it.
A greenish coloured yellow coloured gas with punget odour is evolved which turns moist starch iodide paper blue black.
Now add dil. H₂SO₄ to Lead sulphide and heat.
Colourless gas with rotten egg smell is evolved. The gas evolved turns moist lead acetate paper silvery black.
(v) Iron (II) sulphate is when reacted with small amount of NaOH solution, dirty green precipitates of Iron (II) hydroxide are produced which are insoluble in excess of NaOH.

Iron (III) sulphate is when reacted with small amount of NaOH solution, reddish brown precipitates of Fe(OH)₃ are formed which are insoluble in excess of NaOH.

(vi) Add sol. of NaOH to calcium sulphate solution, milky white ppts. of calcium hydroxide are formed which are soluble in excess of NaOH.

Now add NaOH to zinc sulphate a white ppts of Zn(OH)2 are produced which are soluble in excess of NaOH.

Also when sol. of NH₄OH is add to CaSO₄, no ppts. are formed i. e., no reaction whereas when a sol. of NH₄OH is add to ZnSO₄, gelatinous white ppts. are formed which are soluble is excess of NH₄OH.
(vii) When a sol. of NH₄OH in small amount is added to lead nitrate sol. a chalky white precipitates of lead hydroxide are produced. The precipitats so formed are unsoluble in excess of NH₄OH.

Now add NH₄(OH) in small amount to zinc nitrate, a Gelatinous white precipitates of Zn(OH)₂ are formed which are soluble in excess of NH₄OH.
(viii) When a sol. of NaOH in small amount is added to copper sulphate, pale blue precipitates of copper (II) hydroxide are formed which are insoluble in excess of NaOH.

Now add sol. of NaOH to calcium sulphate sol. milky white ppts. of Ca(OH)₂ are formed which are insoluble in excess of NaOH.
(ix) Test : (i) Add cone. HCl to the sol. and heat, (ii) Filter the sol. after reaction.
Manganese dioxide (Black) : Greenish coloured gas is evolved MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂ Filterate is brownish in colour.
Copper (II) oxide : There is no evolution of chlorine gas. CuO → 2HCl + CuCl₂ + H₂O Filterate is blueish colour.
(x) Dil. HCl is prepared by dissolving HCl gas in water. It ionises to H₃O⁺ and CT ions. HCl gas is prepared by explosive mixture of equal volumes of hydrogen gas and chlorine gas.

Question 3.
Identify the cation (positive ion) and anion (negative ion) in the following substances, A, B and C. Also identify P, Q, R, S, T, U, V, W.
(a) Substance ‘A’is water soluble and gives a curdy white precipitate ‘P’ with silver nitrate solution. ‘P’ is soluble in ammonium hydroxide but insoluble in dil. HNO₃. Substance ‘A’ reacts with ammonium hydroxide solution to give a white precipitate ‘Q’ soluble in excess of NH₄OH.
(b) A solution of substance ‘B’ is added to barium chloride solution. A white ppt. ‘R’ is formed, insoluble in dil. HCl or HNO₃. A dirty green ppt. ‘S’ is formed on addition of ammonium hydroxide to a solution of ‘B’ and the precipitate is insoluble in excess of ammonium hydroxide.
(c) Substance ‘C’ is a coloured, crystalline salt which on heating decomposes leaving a black residue ‘T’. On addition of copper turnings and cone. H₂SO₂ to ‘C’ a coloured acidic gas ‘U’ is evolved on heating. A solution of ‘C’ is added to NaOH soln. until in excess. A pale blue ppt. ‘P’ is obtained insoluble in excess of NaOH. A solution of ‘C’ then added to NH₄ soln. in excess to gives an inky blue solution ‘V’. A solution of ‘C’ is warmed and hydrogen sulphide gas is passed through it. A black ppt. ‘W’ appears.
Answer:

Unit Test Paper — Chemistry Practicals

Q.1. Match the ‘cations’ A to F and the solubility of ppt. G or H with the correct colours from ‘X’ and ‘Y’.

Answer:

Q.2. Select the correct ‘anion’ of a salt from the anions given, which matches with description 1 to 5.

1. The salt soln. reacts with AgNO₃ soln. to give a white ppt. insoluble in dil. HNO₃.
2. The salt soln. reacts with Ba(NO₃)₂ soln. to give a white ppt. insoluble in dil. HNO₃.
3. The salt soln. reacts with Ba(NO₃)₂ soln. to give a white ppt. soluble in dil. HNO₃ but insoluble in dil. H₂SO₄.
4. The salt reacts with dil. H₂SO₄ on heating evolving a gas which turns KMnO₄ soln. pink to colourless.
5. The salt reacts with cone. H₂SO₄ on heating evolving a coloured gas which turns potassium iodide paper brown.

Answer:

1. Cl^– ion(D)
2. SO₄^2-– ion(C)
3. C0₃^2- ion (A)
4. S^2- ion (E)
5. NO₃^1- ion(B)

Q.3. Give balanced equations for the conversions A and B.


Answer:

Q.4. Complete the table given below :

Answer:

Q.5. Select the correct word from the words in bracket.

1. The solution which on heating with CaCO₃ evolves CO₂ gas. [cone. H₂SO₄ / dil.H₂SO₄ / dil. HCl]
2. The solution which can be used to distinguish an ammonium salt from a sodium salt. [CuCl₂ soln. / NH₄OH / dil. H₂SO₄ / AgNO₃ soln.]
3. The pH of blood is around 7.4, of saliva is 6.5 and of acid rain is around 4.5. The solution which is slightly alkaline of the three, [saliva / acid rain / blood]
4. Decomposition of [NaCl / NaHCO₃ / NaNO₃] by dil. H₂SO₄, forms an unstable acid.
5. A metal which reacts with an alkali to liberate hydrogen, [iron / copper / aluminium]

Answer:

1. dil. HCl
2. CuCl₂soln.
3. blood
4. NaHCO₃
5. aluminium.

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New Simplified Chemistry Class 10 ICSE Solutions – Mole Concept and Stoichiometry : Percentage Composition – Empirical & Molecular Formula Calculations Based on Chemical

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Viraf J Dalal Chemistry Class 10 Solutions and Answers

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Additional Problems

Q.1. Percentage Composition

Question 1.
Calculate the percentage by weight of :
(a) C in carbon dioxide
(b) Na in sodium carbonate
(c) Al in aluminium nitride.
[C = 12, O = 16, H = 1, Na = 23, Al = 27, N = 14]
Answer:

Question 2.
Calculate the percentage of iron in K₃Fe(CN)₆. [K = 39,Fe = 56, C = 12, N = 14]
Answer:

Question 3.
Calculate which of the following – calcium nitrate or ammonium sulphate has a higher % of nitrogen.[Ca = 40, S = 32, N = 14, O = 16]
Answer:

Question 4.
Calculate the percentage of pure aluminium in 10kg. of aluminium oxide [Al₂O₃] of 90% purity. [Al = 27, O = 16]
Answer:

Question 5.
State which of the following are better fertilizers —

1. Potassium phosphate [K₃PO₄] or potassium nitrate [KNO₃]
2. Urea [NH₂CONH₂] or ammonium phosphate [(NH₄)₃PO₄]
   [K = 39, P = 31, O = 16, N = 14, H = 1]

Answer:

Question 6.
Calculate the percentage of carbon in a 55% pure sample of carbon carbonate. [Ca = 40, C = 12, O = 16]
Answer:

Question 7.
Calculate the percentage of water of crystallisation in hydrated copper sulphate [CuSO₄.5H₂O].
[Cu = 63.5, S = 32, O = 16, H = 1]
Answer:

Question 8.
Hydrated calcium sulphate [CaSO₄xH₂O] contains 21% of water of crystallisation. Calculate the number of molecules of water of crystallisation Le. ‘X’ in the hydrated compound.
[Ca = 40, S = 32, O = 16, H = 1]
Answer:

Q.2. Empirical And Molecular Formula

Question 1.
A compound gave the following data : C = 57.82%, O = 38.58% and the rest hydrogen. Its vapour density is 83. Find its empirical and molecular formula. [C = 12, O = 16, H = 1]
Answer:

Question 2.
Four g of a metallic chloride contains 1.89 g of the metal ‘X’. Calculate the empirical formula of the metallic chloride. [At. wt. of ‘X’ = 64, Cl = 35.5]
Answer:

Question 3.
Calculate the molecular formula of a compound whose empirical formula is CH₂O and vapour density is 30.
Answer:

Question 4.
A compound has the following percentage composition. Al = 0.2675g.; P = 0.3505g.; O = 0.682g. If the molecular weight of the compound is 122 and its original weight on analysis gave the above results 1.30 g. Calculate the molecular formula of the compounds
[Al = 27, P = 31, O = 16]
Answer:

Question 5.
Two organic compounds ‘X’ and ‘Y’ containing carbon and hydrogen only have vapour densities 13 and 39 respectively. State the molecular formula of ‘X’ and ‘Y’ [C = 12, H = 1]
Answer:

Question 6.
A compound has the following % composition. Zn = 22.65%; S = 11.15%; O = 61.32% and H = 4.88%. Its relative molecular mass is 287 g. Calculate its molecular formula assuming that all the hydrogen in the compound is present in combination with oxygen as water of crystallization.
[Zn = 65, S — 32, O = 16, H = 1]
Answer:

Question 7.
A hydrocarbon contains 82.8% of carbon. Find its molecular formula if its vapour density is 29 [H = 1, C = 12]
Answer:

Question 8.
An organic compound on analysis gave H = 6.48% and O = 51.42%. Determine its empirical formula if the compound contains 12 atoms of carbon.
[C = 12, H = 1, O = 16]
Answer:

Question 9.
A hydrated salt contains Cu = 25.50%, S = 12.90%, O = 25.60% and the remaining % is water of crystallization. Calculate the empirical formula of the salt.
[Cu = 64, S = 32, O = 16, H = 1]
Answer:

Question 10.
A gaseous hydrocarbon weights 0.70 g. and contains 0.60 g. of carbon. Find the molecular formula of the compound if its molecular weight is 70.
[C = 12, H = 1]
Answer:

Question 11.
A salt has the following % composition Al = 10.50%, K = 15.1%, S = 24.8% and the remaining oxygen. Calculate the empirical formula of the salt.
[Al = 27, K = 39, S = 32, O = 16]
Answer:

Q.3. Chemical Equations

Question 1.
What mass of silver chloride will be obtained by adding an excess of hydrochloric acid to a solution of 0.34 g of silver nitrate.
[Cl = 35.5, Ag = 108, N = 14, O = 16, H = 1]
Answer:

Question 2.
What volume of oxygen at s.t.p. will be obtained by the action of heat on 20 g
KClO3 [K = 39, Cl = 35.5, O = 16]
Answer:

Question 3.
From the equation : 3Cu + 8HNO₃ → 3Cu(NO₃)₂ + 4H₂O + 2NO. Calculate

1. the mass of copper needed to react with 63 g of nitric acid
2. the volume of nitric oxide collected at the same time. [Cu = 64, H = 1, O = 16, N = 14]

Answer:

Question 4.
Zinc blende [ZnS] is roated in air. Calculate :

(a) The number of moles of sulphur dioxide liberated by 776 g of ZnS and
(b) The weight of ZnS required to produce 22.4 lits. of SO₂ at s.t.p. [S = 32, O = 16, Zn = 65]

Answer:

Question 5.
Ammonia reacts with sulphuric acid to give the fertilizer ammonium sulphate. Calculate the volume of ammonia [at s.t.p.] used to form 59 g of ammonium sulphate.
[N = 14, H = 1, S = 32, O = 16]
Answer:

Question 6.
Heat on lead nitrate gives yellow lead [II] oxide, nitrogen dioxide and oxygen. Calculate the total volume of NO₂ and O₂ produced on heating 8.5 of lead nitrate.
[Pb = 207, N = 14, O = 16]
Answer:

Question 7.
Calculate the amount of KClO₃ which on thermal decomposition gives ‘X’ vol. of O₂, which is the volume required for combustion of 24 g. of carbon.

[K = 39, Cl = 35.5, O = 16, C = 12].
Answer:

Question 8.
Calculate the weight of ammonia gas.
(a) Required for reacting with sulphuric acid to give 78g. of fertilizer ammonium sulphate.
(b) Obtained when 32.6g. of ammonium chloride reacts with calcium hydroxide during the laboratory preparation of ammonia.
[2NH₄Cl + Ca(OH)₂ → CaCl₂ + 2H₂O + 2NH₃] [N = 14, H = 1, O = 16, S = 32, Cl = 35.5].
Answer:

Question 9.
Sodium carbonate reacts with dil. H₂SO₄ to give the respective salt, water and carbon dioxide. Calculate the mass of pure salt formed when 300 g. of Na₂CO₃ of 80% purity reacts with dil. H₂SO₄.
[Na = 23, C = 12, O = 16, H = 1, S = 32].
Answer:

Question 10.
Sulphur burns in oxygen to give sulphur dioxide. If 16 g. of sulphur burns in ‘x’ cc. of oxygen, calculate the amount of potassium nitrate which must be heated to produce V cc. of oxygen. [S = 32, K = 39, N = 14, O = 16].
Answer:

Question 11.
Sample of impure magnesium is reacted with dilute sulphuric acid to give the respective salt and hydrogen. If 1 g. of the impure sample gave 298.6 cc. of hydrogen at s.t.p. Calculate the % purity of the sample. [Mg = 24, H = 1].
Answer:

Questions

A. Lussac’S Law – Problems based on them

2006

Question 1.
560 ml. of carbon monoxide is mixed with 500 ml of oxygen and ignited. The chemical equation for the reaction is as follows : 2CO + O₂ → 2CO₂. Calculate the volume of oxygen used and carbon dioxide formed in the above reaction.
Answer:

2009

Question 1.
200 cm³ of acetylene is formed from a certain mass of calcium carbide, find the volume of oxygen required and carbon dioxide formed during the complete combustion. The combustion reaction can be represented as below.
2C₂H₂(g) + 5O₂ (g) → 4CO₂ (g) + 2H₂O (g)
Answer:

2010

Question 1.
10 litre of this mixture is burnt, And the total volume of carbon dioxide gas added to the atmosphere. Combustion reaction can be represented as :


Answer:

2012

Question 1.
67.2 litres of H₂ combines with 44.8 litres of N₂ to form NH₃ :
N₂(g) + 3H₂(g) → 2NH₃(g). Calculate the vol. of NH₃ produced. What is the substance, if any, that remains in the resultant mixture ?
Answer:

2013

Question 1.
What volume of oxygen is required to burn completely 90 dm³ of butane under similar conditions of temperature and pressure?
2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O
Answer:

2014

Question 1.
What volume of ethyne gas at s.t.p. is required to produce 8.4 dm³ of carbon dioxide at s.t.p.?
2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O [H = 1, C = 12, O = 16]
Answer:

2015

Question 1.
If 6 litres of hydrogen and 4 litres of chlorine are mixed and exploded and if water is added to the gases formed, find the volume of the residual gas.
Answer:

2016

Question 1.
The equations 4NH₃ + 5O₂ → 4NO + 6H₂O, represents the catalytic oxidation of ammonia. If 100 cm3 of ammonia is used calculate the volume of oxygen required to oxidise the ammonia completely.
Answer:

2017

Question 1.
Propane burns in air according to the following equation :
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O. What volume of propane is consumed on using 1000 cm3 of air, considering only 20% of air contains oxygen.
Answer:

B. Mole Concept – Avogadro’S Number – Problems based on them

2004

Question 1.
A flask contains 3.2 g of SO₂. Calculate :

1. The moles of SO₂ and the no. of molecules of SO₂ present in the flask.
2. The volume occupied by 3.2 g. of SO₂ at s.t.p. (S = 32, O = 16)

Answer:

Question 2.
2KMnO₄ → K₂MnO₄ + MnO₂ + O₂ Given that the molecular mass KMn04 is 158, what volume of oxygen (measured at room temperature) would be obtained by the complete decomposition of 15.8 g. of potassium permanganate. (Molar volume at room temperature is 24 litres.)
Answer:

2005

1. The volumes of gases A, B, C and D are in the ratio, 1 : 2 : 2 : 4 under the same conditions of temp, and press.

(i) Which sample contains the maximum number of molecules. If the temp, and pressure of gas A are kept constant, then what will happen to the volume of A when the no. of molecules is doubled.
Answer:
The sample D and volume of A will get Doubled.

(ii) If this ratio of gas vols. refers to reactants and products of reaction – gas law observed is ….
Answer:
Gay Lussac’s law of combining volumes.

(iii) If the volume of ‘A’ is 5.6 dm³ at s.t.p., calculate the no. of molecules in the actual vol. of ‘D’ at s.t.p. (Avog no. is 6 × 10²³). Using your answer, state the mass of ‘D’ if the gas is “N2O” (N = 14, O = 16). [6 x 1023, 44g.]
Answer:
Vol. of D will be 4 × 5.6 = 22.4 lit. and 22.4 lit. of D contain molecules = 6 × 10²³ (AV. number)
Mass of N₂ O (i.e. D) = (14 × 2 + 16 × 1) = 44g

2006

Question 1.
Calculate the no. of moles and the no. of molecules present in 1.4 g of ethylene gas (C₂H₄). What is the vol. occupied by the same amount of C₂H₄. State the vapour density of C₂H₄.
(Avog. No. = 6 × 10²³ ; C = 12, H = 1]
(0.05 moles ; 3 × 10²² molecules ; 1.12 lit. ; 14)
Answer:

2008

1. The equation for the burning of octane is : 2C₈H₁₈ + 25O₂ → 16CO₂ + 18H₂O

(i) How many moles of carbon dioxide are produced when one mole of octane burns ?
Answer:
2 moles of octane produce 16 moles of C0₂
1 mole of octane will produce 16/2 moles of C0₂ = 8 moles of carbon dioxide.

(ii) What volume, at s.t.p., is occupied by the number of moles determined in (1) (i) ?
Answer:
1 moles occupy a volume of 22.4 litres.
8 mole will occupy a volume of = 22.4 × 8 = 179.2 litres

(iii) If the relative molecular mass of carbon dioxide is 44, what is the mass of carbon dioxide produced by burning two moles of octane ?
Answer:
From equation, we know that 2moles of octane produces 16 moles of CO₂.
Mass of CO₂ produced = 16 × 44 = 704

2009

Question 1.
Define the term – Mole. A gas cylinder contains 24 × 10²⁴ molecules of nitrogen gas. If Avogadro’s number is 6 × 10²³ and the relative atomic mass of nitrogen is 14, calculate :

1. Mass of nitrogen gas in the cylinder.
2. Volume of nitrogen at STP in dm³

Answer:

Question 2.
Gas ‘X’ occupies a volume of 100 cm³ at S.T.P and weighs 0.5 g. find its relative molecular mass.
Answer:

2010

Question 1.
Dilute hydrochloric acid (HCl) is reacted with 4.5 moles of calcium carbonate. Give the equation for the said reaction. Calculate :

1. The mass of 4.5 moles of CaCO₃.
2. The volume of CO₂ liberated at stp.
3. The mass of CaCl₂ formed ?
4. The number of moles of the acid HCl used in the reaction (relative molecular mass of CaCO₃ is 100 and of CaCl₂ is 111].

Answer:

2011

Question 1.
Calculate the mass of :

1. 10²² atoms of sulphur.
2. 0.1 mole of carbon dioxide.
   [S = 32, C = 12 and O = 16 and Avogadro’s Number 6 × 10²³]

Answer:

Question 2.
Calculate the volume of 320 g of SO₂ at stp. [S = 32 and O = 16]
Answer:

2012

Question 1.
The mass of 5.6 dm³ of a certain gas at STP is 12.0 g. Calculate the relative molecular mass of the gas.
Answer:

2013

Question 1.
The vapour density of a gas is 8. What would be the volume occupied by 24.0 g of the gas at STP ?
Answer:

Question 2.
Calculate the volume occupied by 0.01 mole of CO₂ at STP.
Answer:

2014

Question 1.
State Avogadro’s Law. A cylinder contains 68g of ammonia gas at s.t.p.

1. What is the volume occupied by this gas?
2. How many moles and how many molecules ammonia are present in the cylinder? [N = 14, H = 1]

Answer:

2015

Question 1.
From A, B, C, D, which weighs the least —
A : 2 g. atoms of Nitrogen
B : 1 mole of Silver
C : 22.4 litres of oxygen gas at 1 atmospheric pressure and 273K
D : 6.02 × 1o²³ atoms of carbon.
[Ag = 108, N=14, 0=16, C=12]
Answer:
D : 6.02 × 10²³ atoms of carbon.

Question 2.
Calculate the mass of Calcium that will contain the same number of atoms as are present in 3.2 gm of sulphur. [S = 32, Ca = 40]
Answer:

2016

Question 1.
Select the correct answer from A, B, C and D : The ratio between the number of molecules in 2g of hydrogen and 32g of oxygen is: k

(A) 1 : 2
(B) 1 : 0.01
(C) 1:1
(D) 0.01 : 1
[H = 1, O = 16]

Answer:

(C) 1 : 1

Question 2.
A gas of mass 32 gms has a volume of 20 litres at S.T.P. Calculate the gram mol. weight of the gas.
Answer:

Question 3.
A gas cylinder contains 12 x 1024 molecules of oxygen gas. Calculate :

1. the mass of 02 present in the cylinder.
2. the volume of O₂ at S.T.P. present in the cylinder.[0 = 16] Avog. no. is 6 × 10²³ [640g. ; 448 l]

Answer:

2017

Question 1.
Calculate the number of gram atoms in 4.6 grams of sodium [Na = 23]
Answer:

Question 2.
The mass of 11.2 litres of a certain gas at s.t.p. is 24 g. Find the gram molecular mass of the gas.
Answer:

C. Mole Concept – Avogadro’S Law – problmes based on them

2001

Question 1.
The gases chlorine, nitrogen, ammonia and sulphur dioxide are collected under the same conditions of temperature and pressure. If 20 litres of nitrogen contain ‘X’ no. of molecules state the no. of molecules in 10 litres of chlorine, 20 litres of ammonia and 5 litres of sulphur dioxide, (x/2, x, x/4)

Answer:

2002

Question 1.
Samples of gases O₂, N₂, CO and CO₂ under the same conditions of temperature and pressure contain the same number of molecules represented by X. The molecules of oxygen occupy V litres and have a mass of 8 g. Under the same conditions of temperature and pressure, what is the volume occupied by :

1. X molecules of N₂.
2. 3X molecules of CO.
3. What is the mass of CO₂ in grams.
4. In answering the above questions, whose law has been used.
   (C = 12, N = 14, O = 16)

Answer:

2005

Question 1.
Define the term atomic weight :
Answer:
Atomic weight : is the number of times one atom of an element is heavier than 1/2 the mass of an atom of carbon (C¹²)

2008

Question 1.
The gas law which relates the volume of a gas to the number of molecules of the gas is :

A Avogadro’s Law
B Gay-Lussac’s Law
C Boyle’s Law
D Charle’s Law

Answer:

A Avogadro’s Law

2009

Question 1.
Correct the following – Equal masses of all gases under identical conditions contain the same number of molecules.
Answer:
Equal volumes of all gases under identical conditions contain the same number of molecules.

2013

Question 1.
A vessel contains X number of molecules of hydrogen gas at a certain temperature & pressure. Under the same conditions of temperature & pressure, how many molecules of nitrogen gas would be present in the same vessel.
Answer:
According to Avogadro’s law, equal volume of all gases under similar conditions of temperature and pressure contain equal number of molecules.
Hence, number of molecules of N₂ = Number of molecules of H₂ = X

2017

Question 1.
A gas cylinder can hold 1 kg. of H₂ at room temp. & press.:

1. Find the number of moles of hydrogen present
2. What weight of CO₂ can the cylinder hold under similar conditions to temp. & press
3. If the number of molecules of hydrogen in the cylinder is X, calculate the number of CO₂ molecules in the cylinder under the same conditions of temp. & press
4. State the law that helped you to arrive at the above result.

Answer:

1. 2 g of hydrogen gas = 1 mole.
   ∴ 1000 g of hydrogen gas 1000/2 = 500 moles.
2. 1 mole of carbon dioxide = 44 g
   ∴ 500 moles of carbon dioxide = 44 x 500 = 22000 g = 22 kg Weight of carbon dioxide in cylinder = 22 kg
3. Equal volumes of all gases under similar conditions of temperature and pressure contain equal number of molecules.
   ∴ Molecules in the cylinder of carbon dioxide = X.
4. Avogadro’s law.

D. Vapour Density & Molecular Weight – Problems based on them

1996

Question 1.
Find the relative molecular mass of a gas, 0.546 g of which occupies 360 cm3 at 87°C and 380 mm Hg pressure. (1 litre of hydrogen at s.t.p. weighs 0.09 g)
Answer:

2001

Question 1.
Mention the term defined by the following : The mass of a given volume of gas compared to the mass of an equal volume of hydrogen.
Answer:
Vapour Density.

2004

Question 1.
Some potassium permanganate was heated in a test tube. After collecting one litre of oxygen at room temperature, it was found that the test tube had undergone a loss in a mass of 1.32 g. If one litre of hydrogen under the same conditions of temperature and pressure has a mass of 0.0825 g. Calculate the relative molecular mass of oxygen.

Answer:

2009

Question 1.
A gas cylinder of capacity of 20 dm³ is filled with gas X the mass of which is 10 g. When the same cylinder is filled with hydrogen gas at the same temperature and pressure the mass of the hydrogen is 2g, hence the relative molecular mass of the gas is :

(A) 5
(B) 10
(C) 15
(D) 20

Answer:

(B) 10

2012

Question 1.
The vapour density of carbon dioxide [C = 12, O = 16] is

(A) 32
(B) 16
(C) 44
(D) 22

Answer:

(D) 22

2014

Question 1.
Give one word or phrase for : The ratio of the mass of a certain volume of gas to the mass of an equal volume of hydrogen under the same conditions of temperature and pressure.
Answer:
Vapour density.

E. Percentage Composition – Problems based on them

1996

Question 1.
Find the total percentage of oxygen in magnesium nitrate crystals : Mg(NO₃)₂. 6H₂O
(H = 1, N = 14, O = 16, Mg = 24)
Answer:

1997

Question 1.
What is the mass of nitrogen in 1000 kg of urea [CO(NH₂)₂].[C = 12] (Answer to the nearest kg.)
Answer:

1998

Question 1.
Calculate the % of boron (B) in borax Na₂ B₄ O₇. 10H₂O. (H = 1, B = 11, O = 16, Na = 23)
Answer:

1999

Question 1.
If a crop of wheat removes 20 kg of nitrogen per hectare of soil, what mass in kg. of the fertilizer calcium nitrate would be required to replace the nitrogen in a 10 hectare field. (N = 14 ; O = 16 ; Ca = 40)
Answer:

2001

Question 1.
Calculate the percentage of phosphorus in the fertilizer superphosphate Ca(H₂PO₄)₂. (correct to 1dp) (H = 1 ; O = 16 ; P = 31 ; Ca = 40)
Answer:

2002

Question 1.
Calculate the percentage of platinum in ammonium chloroplatinate (NH₄)₂ PtCl₆
(Give your answer correct to the nearest whole number). (N = 14, H = 1, Cl = 35.5, Pt = 195)
Answer:

2005

Question 1.
Calculate the percentage of nitrogen in aluminium nitride. (Al = 27, N = 14)
Answer:

2006

Question 1.
Calculate the percentage of sodium in sodium aluminium fluoride (Na₃AlF₆) correct to the nearest whole number. (F = 19 ; Na = 23 ; A1 = 27)
Answer:

2007

Question 1.
Determine the percentage of oxygen in ammonium nitrate (O = 16)
Answer:

2010

Question 1.
If the relative molecular mass of ammonium nitrate is 80, calculate the percentage of nitrogen and oxygen in ammonium nitrate. (N = 14, H = 1, O = 16).
Answer:

2012

Question 1.
Find the total percentage of Magnesium in magnesium nitrate crystals, Mg(NO₃)₂.6H₂O/ [Mg = 24; N = 14; O = 16 and H = 1]
Answer:

2017

Question 1.
Calculate the percentage of water of crystallization in CUSO₄.5H₂O. [H = 1, O = 16, S = 32, Cu = 64]
Answer:

F. Empirical Formula And Molecular Formula – Problems based on then

2000

Question 1.
Determine the empirical formula of the compound whose composition by mass is : 42% nitrogen 48% oxygen and 9% hydrogen.
(H = 1 ; N = 14 ; O 16).
Answer:

2001

Question 1.
A metal M forms a voltaic chloride containing 65.5% chlorine. If the density of the chloride relative to hydrogen (i.e. V.D.) is 162.5, find the molecular formula of the chloride. (M = 56, Cl = 35.5)
Answer:

2002

Question 1.
The percentage composition of sodium phosphate as determined by analysis is 42.1% sodium, 18.9% phosphorus and 39% oxygen. Find the empirical formula of the compound (work to two decimal places). (Na = 23, P = 31, O = 16)
Answer:

2004

Question 1.
An experiment showed that in a lead chloride solution, 6.21 g of lead combined with 4.26 g. of chlorine. What is the empirical formula of this chloride. (Pb = 207 ; Cl = 35.5)
Answer:

2006

Question 1.
Determine the empirical formula of a compound containing 47.9% potassium, 5.5% beryllium and 46.6% fluorine by mass.
(At. weight of Be = 9 ; F = 19 ; K = 39) Work to one decimal place.
Answer:

2007

Question 1.
A compound X consists of 4.8% carbon and 95.2% bromine by mass

1. Determine the empirical formula of this compound working correct to one decimal place
2. If the vapour density of the compound is 252, what is the molecular formula of the compound. (C = 12 ; Br = 80) (CBr₃, C₂Br₆).

Answer:

2008

Question 1.
What is the empirical formula of octane (C₈H₁₈) ?
Answer:
M.F. of octane = C₈H₁₈ = (c₄H₉)₂
∴ E.F. of octane = C₄H₉

Question 2.
A compound has the following percentage composition by mass, Carbon 14.4%, hydrogen 1.2% and chlorine 84.5%. Determine the empirical formula of this compound. Work correct to 1 decimal place. The relative molecular mass of this compound is 168, so what is its molecular formula?
(H = 1 ; C = 12 ; Cl = 35.5)
Answer:

2009

Question 1.
A gaseous compound of nitrogen and hydrogen contains 12.5% hydrogen by mass. Find the molecular formula of the compound if its relative molecular mass is 37.
[N =14, H = 1].
Answer:

2011

Question 1.
An organic compound with vapour density 94. It contains C = 12.67%, H = 2.13%, and Br = 85.11%. Find the molecular formula of the organic compound.
[C = 12, H = 1, Br = 80]
Answer:

2014

Question 1.
A compound having empirical formula X₂Y is made of two elements X and Y. Find its molecular formula. If the atomic weight of X is 10 and that of Y is 5 and the compound has a vapour density 25.
Answer:

2015

Question 1.
If the empirical formula of a compound is CH and it has a vapour density of 13, find the molecular formula of the compound. [C = 12, H = 1]
Answer:

2016

Question 1.
A gaseous hydrocarbon contains 82.76% of carbon. Given that its vapours density is 29, find its molecular formula. [C=12,H=1]
Answer:

2017

Question 1.
A compound of X and Y has the empirical formula XY₂. Its vapou density is equal to its empirical formula weight. Determine its Molecular formla.
Answer:

G Chemical Equations – Problems based on them

2000

Question 1.
Washing soda has the formula Na₂CO₃.10H₂O. What mass of anhydrous sodium carbonate is left when all the water of crystallization is expelled by heating 57.2 g of washing soda.
Answer:

Question 2.
Na₂SO₄ + Pb(N0₃)₂ → PbSO₄ + 2NaNO₃ When excess » lead nitrate solution was added to a solution of sodium sulphate, 15.15 g of lead sulphate were precipitated. What mass of sodium sulphate was present in the original solution. (H = 1 ; C = 12 ; O = 16 ; Na = 23; S = 32 ; Pb = 207)
Answer:

2001

Question 1.
From the equation : (NH₄)₂ Cr₂O₇ → Cr₂O₃ + 4H₂O + N₂ Calculate :

1. the vol. of nitrogen at STP, evolved when 63g. of ammonium dichromate is heated. (5.6 lits.)
2. the mass of Cr₂O₃ formed at the same time. (N = 14, H = 1, Cr = 52, O = 16) (38 g.)

Answer:

2003

Question 1.
10g. of a mixture of NaCI and anhydrous Na₂SO₄ is dissolved in water. An excess of BaCl₂ soln. is added and 6.99 g. of BaSO is precipitated according to the equation :
Na₂SO₄ + BaCl₂ → BaSO₄ ↓+ 2NaCl. Calculate the percentage of sodium sulphate in the original mixture.
(O = 16 ; Na = 23 ; S = 32; Ba = 137)
Answer:

2004

Question 1.
The reaction of potassium permanganate with acidified iron (II) sulphate is given below :
2KMnO₄ + 10FeSO₄ + 8H₂SO₄ → K₂SO₄ + 2MnSO₄ + 5 Fe₂(SO₄)₃ + 8H₂O.
If 15.8 g. of potassium permanganate was used in the reaction, calculate the mass of iron (II) sulphate used in the above reaction.
(K = 39, Mn = 55, Fe = 56, S = 32, O = 16)
Answer:

2005

Question 1.
The equation given below relate to the manufacture of sodium carbonate (Mol), wt. of Na₂CO₃ = 106

1. NaCl + NH₃ + CO₂ + H₂O → NaHCO₃ + NH₄Cl
2. 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂

Questions (a) and (b) are based on the production of 21.2 g. of sodium carbonate.
(a) What mass of sodium hydrogen carbonate must be heated to give 21.2 g. of sodium carbonate (Molecular weight of NaHCO₃ = 84).
(b) To produce the mass of sodium hydrogen carbonate calculated in (a), what volume of carbon dioxide, measured at s.t.p., would be required.
Answer:

2006

Question 1.
The relative molecular mass (mol. wt.) of copper oxide is 80. What vol. of HN₃ (measured at s.t.p.) is required to completely reduce 120 g of cuO.
(3CuO + 2NH₃ → 3Cu + 3H₂O + N₂].
Answer:

2007

Question 1.
A sample of ammonium nitrate when heated yields 8.96 litres of steam (measured at stp.)
NH₄ NO₃ → N₂O + 2H₂O

1. What volume of dinitrogen oxide is produced at the same time as 8.96 litres of steam.
2. What mass of ammonium nitrate should be heated to produce 8.96 litres of steam (Relative molecular mass of NH₄NO₃ is 80)

Answer:

2008

Question 1.
From the equation :
C + 2H₂SO₄ → CO₂ + 2H₂O + 2SO₂
Calculate :

1. The mass of carbon oxidised by 49 g of sulphuric acid (C = 12 ; relative molecular mass of sulphuric acid = 98).
2. The volume of SO₂ measured at s.t.p., liberated at the same time.

Answer:

2009

Question 1.
Commercial NaOH weighing 30 g. has some NaCl in it. The mixture on dissolving in water and treatment with excess AgNO₃ soln. formed a precipitate weighing 14.3 g. What is the percentage of NaCl in the commercial sample of NaOH.
NaCl + AgNO₃ → AgCl + NaNO₃
[Relative molecular mass of NaCl = 58 ; AgCl = 143]
Answer:

2011

Question 1.
Calculate the volume of oxygen required for the complete combustion of 8.8g of propane (C₃ H₈). (C = 12, O = 16, H = 1, Molar Volume = 22.4 dm³ at stp)
Answer:

2013

Question 1.

Answer:

2015

Question 1.
From the equation :

Calculate:

1. the quantity in moles of (NH₄)₂Cr₂O₇ if 63gm oft[NH₄)₂Cr₂O₇ is heated.
2. the quantity in moles of nitrogen formed.
3. the volume in litres or dm³ of N₂ evolved at s.t.p.
4. the mass in grams of Cr₂O₃ formed at the same time. [H=l, Cr= 52, N=14]

Answer:

2016

Question 1.
How much calcium oxide is formed when 82g. of calcium nitrate is heated. Also find the volume of nitrogen dioxide evolved :
2Ca(NO₃)2 → 2CaO + 4NO₂ + O₂ (Ca = 40, N = 14, O = 16)
Answer:

For More Resources

New Simplified Chemistry Class 10 ICSE Solutions – Mole Concept and Stoichiometry : Gay Lussac’s Law – Avogadro’s Law

ICSE SolutionsSelina ICSE SolutionsML Aggarwal Solutions

Viraf J Dalal Chemistry Class 10 Solutions and Answers

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Practice Questions

Question 1.
What volume of oxygen would he required to burn completely 400 ml of acetylene (C₂H₂) ? Calculate the volume of CO₂ formed.
Answer:

Question 2.
2500 cc of oxygen was burnt with 600 cc of ethane (C₂H₆). Calculate the volume of unused oxygen and the volume of carbon dioxide formed, after writing the balanced equation :
Ethane + Oxygen → Carbon dioxide + Water vapour
Answer:

Question 3.
80 cm³ of methane are mixed with 200 cm³ of pure oxygen at similar temperature and pressure. The mixture is then ignited. Calculate the composition of resulting mixture if it is cooled to initial room temperature and pressure.
CH₄ + 2O₂ → CO₂ + 2H₂O
Answer:

Question 4.
Calculate the volume of HCl gas formed and chlorine gas required when 40 mL of methane reacts completely with chlorine at S.T.P.
CH₄ + 2Cl₂ → CH₂Cl₂ + 2HCl
Answer:

Question 5.
What volume of propane is burnt for every 500 cm³ of air used in the reaction under the same conditions ?
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
Answer:

Question 6.
450 cm³ of nitrogen monoxide and 200 cm³ of oxygen are mixed together and ignited. Calculate the composition of resulting mixture.
2NO + O₂ → 2NO₂
Answer:

Question 7.
24 cc marsh gas (CH₄) was mixed with 106 cc oxygen and then exploded. On cooling the volume of the mixture became 82 cc of which 58 cc were unchanged oxygen. Which law does their experiment supports ? Explain with calculations.
Answer:


Avogadro’s Law : “Under the same conditions of temperature and pressure equal volumes of all gases contain die same number of molecules.”
If we assume that 7 litre of oxygen gas contains ‘n’ molecules of the gas then by Avogadro’s Law :

1. 1 litre of oxygen will contain ‘n’ molecules of hydrogen
2. 1 litre of nitrogen will contain ‘n’ molecules of nitrogen.
3. 1 litre of any gas will contain ‘n’ molecules of that gas. e.g.

Relative Molecular Mass : “It is the number that represents how many times one molecule of a substance is heavier than one atom of hydrogen whose weight has been taken unity or 1/12 of ₆C¹².
Relative Molecular Mass : “It is the number that represents how many times one molecule of a substance is heavier than one atom of hydrogen whose weight has been taken unity or 1/12 of ₆C¹².
Avogadro’s Number : “The number of atoms present in 12 g (gm atomic mass) of ₆C¹² is called Avogadro’s number.
Na or L = 6.023 × 10²³

Mole : Mole is the mass of substance containing particles equal to Avogadro’s number i.e. 6.023 × 10²³.
Gram Atom : “The relative atomic mass of an element expressed in grams is called gram atom.
Gram Mole : “The relative atomic mass of a substance expressed in grams is called gram mole.
Molar Volume : Volume occupied by one mole of any gas at STP is called molar volume.

Applications Of Avogadro’S Law :

1. Determines the atomicity of the gas.
2. Determines the molecular formula of a gas.
3. Determines the relation between molecular weight and vapour density.
4. Explains Gay-Lussac’s law.
5. Determines the relationship between gram molecular weight and gram molecular volume.

1. Determines the atomicity of a gas :
Atomicity : The number of atoms present in one molecule of that element is called atomicity.
Monoatomic : Elements which have one atom in their molecules e.g. Helium, Neon.
Diatomic : Elements which have two atoms in their molecule e.g. Hydrogen, nitrogen, oxygen.
e.g. of Determination of atomicity of a gas :

A molecules of nitrogen contains two atoms : atomicity – Diatomic

2. Determines the molecular formula of a gas.
Molecular formula : A chemical formula which gives the actual or exact number of atoms of the elements present in one molecule of a compound.

3. Determines the relation between molecular weight and vapour density.
Molecular weight: It is the ratio of the weight of 1 molecule of a substance to the weight of one atom of hydrogen.

Vapour Density : It is the ratio of the mass of a certain volume of gas or vapour of the mass of the same volume of hydrogen.
Mol. wt. = 2× vapour density

4. Explains Gay-Lussac’s Law :
Gay-Lussac’s Law is explained by Avogadro’s Law which states “Under similar conditions of temperature and pressure, equal volumes of different gases have same number of molecules.”
Since substances react in simple ratio of number of molecules, volumes of gaseous reactants and products will also bear a simple ratio to one another. This is what Gay-Lussac’s Law says.

5. Determines relationship between gram molecular mass and gram molecular volume :
Gram molecular mass is the relative molecular mass of a substance expressed in grams. It is also called gram molecule of that element.
Gram molecular volume : The volume occupied by e.g. molecular wt. of a gas at s.t.p.

Additional Problems

Q.1. Lussac’S Law

Question 1.
Nitrogen reacts with hydrogen to give ammonia. Calculate the volume of the ammonia gas formed when nitrogen reacts with 6 litres of hydrogen. All volumes measured at s.t.p.
Answer:

Question 2.
2500 cc of oxygen was burnt with 600 cc of ethane [C₂H₆]. Calculate the volume of unused oxygen and the volume of carbon dioxide formed.
Answer:

Question 3.
20 ml. each of oxygen and hydrogen and 10 ml. of carbon monoxide are exploded in an enclosure. What will be the volume and composition of the mixture of the gases when they are cooled to room temperature.
Answer:

Question 4.
224 cm³ of ammonia undergoes catalytic oxidation in presence of Pt to given nitric oxide and water vapour. Calculate the volume of oxygen required for the reaction. All volumes measured at room temperature and pressure.
Answer:

Question 5.
Acetylene [C₂H₂] burns in air forming carbon dioxide and water vapour. Calculate the volume of air required to completely burn 50 cm³ of acetylene. [Assume air contains 20% oxygen].
Answer:

Question 6.
On igniting a mixture of acetylene [C₂H₂] and oxygen, 200 cm³ of CO₂ is collected at s.t.p. Calculate the volume of acetylene & O₂ at s.t.p. in the original mixture.
Answer:

Question 7.
Ammonia is formed from the reactants nitrogen and hydrogen in presence of a catalyst under suitable conditions. Assuming all volumes are measured in litres at s.t.p. Calculate the volume of ammonia formed if only 10% conversion has taken place.
Answer:

Question 8.
100 cc. each of water gas and oxygen are ignited and the resultant mixture of gases cooled to room temp. Calculate the composition of the resultant mixture. [Water gas contains CO and H₂ in equal ratio]
Answer:

Q.2. Mole Concept – Avogadro’S Law – Avogadro’S Number
Calculate the following : [all measurement at s.t.p. or as stated in the problem]

Question 1.
The mass of 2.8 litres of C0₂. [C = 12, O = 16]
Answer:

Question 2.
The volume occupied by 53.5g of Cl₂. [Cl = 35.5]
Answer:

Question 3.
The number of molecules in 109.5 g of HCl. [H = 1, Cl = 35.5]
Answer:

Question 4.
The number of

1. molecules [S = 32]
2. atoms in 192 g. of sulphur. [S₈]

Answer:

Question 5.
The mass of (Na) sodium which will contain 6.023 × 10²³ atoms. [Na = 23]
Answer:

Question 6.
The no. of atoms of potassium present in 117 g. of K. [K = 39]
Answer:

Question 7.
The number of moles and molecules in 19.S6 g. of Pb (NO₃)₂. [Pb = 207, N = 14, O = 16]
Answer:

Question 8.
The mass of an atom of lead [Pb = 202].
Answer:

Question 9.
The number of molecules in 1 1/2 litres of water. [density of water 1.0 g./cm³. — ∴ mass of water = volume × density]
Answer:

Question 10.
The gram-atoms in 88.75 g of chlorine [Cl = 35.5]
Answer:

Question 11.
The number of hydrogen atoms in 0.25 mole of H₂SO₄.
Answer:

Question 12.
The gram molecules in 21 g of nitrogen [N = 14]
Answer:

Question 13.
The number of atoms in 10 litres of ammonia [N = 14, H = 1]
Answer:

Question 14.
The number of atoms in 60 g of neon [Ne = 20]
Answer:

Question 15.
The number of moles of ‘X’ atoms in 93 g of ‘X’ [X is phosphorus = 31]
Answer:

Question 16.
The Volume occupied by 3.5 g of O₂ gas at 27°C and 740 mm presure. [O = 16]
Answer:

Question 17.
The moles of sodium hydroxide contained in 160 g of it. [Na = 23, O = 16, H = 1]
Answer:

Question 18.
The weight in g. of 2.5 moles of ethane [C₂H₆]. [C = 12, H = 1]
Answer:

Question 19.
The molecular weight of 2.6 g of a gas which occupies 2.24 lits. at 0°C and 760 mm press.
Answer:

Question 20.
The gram atoms in 46 g of sodium [Na = 23]
Answer:

Question 21.
The number of moles of KCl0₃ that will be required to give 6 moles of oxygen.
Answer:

Question 22.
The weight of the substance of its molecular weight is 70 and in the gaseous form occupies 10 lits. at 27°C and 700 mm pressure.
Answer:

Question 23.
Has higher number of moles : 5 g. of N₂O or 5 g. of NO [N = 14, O = 16]
Answer:

Question 24.
Has higher mass : 1 mole of CO₂ or 1 mole of CO [C = 12, O = 16]
Answer:

Question 25.
Has higher no. of atoms : 1 g of O₂ or 1 g of Cl₂ [O = 16, Cl = 35.5]
Answer:

Q.3. Vapour Density And Molecular Weight

Question 1.
500 ml. of gas ‘X’ at s.t.p. weighs 0.50 g. Calculate the vapour density and molecular weight of the gas. [1 lit. of H₂ at s.t.p. weighs 0.09 g].
Answer:

Question 2.
A gas cylinder holds 85 g of a gas ‘X’. The same cylinder when filled with hydrogen holds 8.5 g of hydrogen under the same conditions of temperature and pressure Calculate the molecular weight of ‘X’.
Answer:

Question 3.
Calculate the relative molecular mass [molecular weight] of 290 ml. of a gas ‘A’ at 17°C and 1520 mm pressure which weighs 2.73 g at s.t.p. [1 litre of hydrogen at s.t.p. weighs 0.09 g.]
Answer:

Question 4.
State the volume occupied by 40 g of a hydrocarbon – CH₄ at s.t.p. if its V.D. is 8.
Answer:

Question 5.
Calculate the atomcity of a gas X [at. no. 35.5] whose vapour density is equal to its relative atomic mass.
Answer:

Question 6.
Calculate the relative molcular mass and vapour density of methyl alcohol [CH₃OH] if 160 g. of the alcohol on vaporization has a volume of 112 litres at s.t.p.
Answer:

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