ICSE Class 9 Chemistry Sample Question Paper 9 with Answers

ICSE Class 9 Chemistry Sample Question Paper 9 with Answers

Section -1
(Attempt all questions from this section)

Question 1.
(a) Fill in the blanks with the correct choice given in brackets.
1. Mass number of an element is the total number of………………… and neutrons present in its nucleus.  [protons/electrons]
2. ……………….. and ………………… are bridge elements. [Li and Mg/Na and Ca]
3. The chemical reaction in which heat is liberated is known as………………… [endothermic/exothermic]
4. The electrons present in the ………………. shell of an atom are called valence electrons. [innermost/outermost]
5. The molecular formula of quick lime is……………… [Ca(OH)₂/CaO]
Answer:
(i) Protons
(ii) Li and Mg
(iii) Exothermic
(iv) Outermost
(v) Ca(OH)₂

(b) Choose the correct answer from the options given below :
(i) The gas that prevents haemoglobin from carrying blood to different parts of the body is :
(A) Sulphur dioxide
(B) Carbon monoxide
(C) Hydrogen sulphide
(D) Methane
Answer:
(B) Carbon monoxide

(ii) According to Mendeleev’s periodic law the physical and chemical properties of elements are a periodic function of their :
(A) Atomic number
(B) Atomic masses
(C) Atomic weight
(D) Mass number
Answer:
(B) Atomic masses

(iii) The specific value of the amount of heat energy required by ice to change into water is :
(A) 336 J/g
(B) 80 cal/g
(C) 2268 J/g
(D) Both A and B
Answer:
(D) Both A and B

(iv) The graph of PV vs. P for a gas is :
(A) Parabolic
(B) Hyperbolic
(C) A straight line parallel to x
(D) A straight line parallel to y axis
Answer:
(C) A straight line parallel to x

(v) The property which is a characteristic of an equivalent compound is :
(A) They are weak electrolyte.
(B) They are non-volatile.
(c) They conduct electricity in the solid state.
(D) They are soluble in organic solvents.
Answer:
(B) They are non-volatile.

(c) Name the gas evolved in each of the following cases :
(i) When zinc reacts with dilute sulphuric acid.
(ii) When copper carbonate decomposes on heating.
(iii) When chlorine is exposed to sunlight.
(iv) When an electric current is passed through accumulated water.
(v) When nitrogen tetraoxide is heated.
Answer:
(i) Hydrogen
(ii) Carbon dioxide
(iii) Oxygen
(iv) Hydrogen and Oxygen
(v) Nitrogen dioxide

(d) Give a reason for each of the following :
(i) Why elements of group numbers 3 to 12 are known as transition elements ?
(ii) Why the valency of all elements in a group is same ?
(iii) Why hydrogen is called inflammable air ?
(iv) Why washing soda when exposed to dry air becomes a monohydrate ?
(v) Why group 1 elements in periodic table are known as alkali metals ?
Answer:
(i) Elements of group numbers from 3 to 12 are known as transition elements because they have their two outermost shells incomplete.

(ii) Since elements in a particular group have an equal number of electrons in their respective valence shells, thus the valency of all elements in a group is same.

(iii) Hydrogen gas is called inflammable air because of its combustible nature.

(iv) Washing soda when exposed to dry air becomes a monohydrate because it loses its water of crystallisation.

(v) Group 1 elements are known as alkali metals because they react with water to form their hydroxides which are strong alkalies.

(e) What do you observe when :
(i) Alkali metals react with water.
(ii) Halogens react directly with metal.
(iii) Aluminium reacts with steam.
(iv) The temperature of sodium nitrate, potassium nitrate and potassium bromide is increased.
(v) Iron nails are added to blue coloured copper sulphate solution.
Answer:
(i) They react with water to produce hydrogen.
2M + 2H₂O → 2MOH + H₂ Where M is alkali metal.
(ii) They form metal halides or salts.
(iii) It liberates hydrogen.
(iv) When the temperature is increased their solubility decreases.
(v) The blue colour of the solution fades and eventually turns into light green due to formation of ferrous sulphate.

(f) (i) State Charle’s law.
(ii) Write 2 behaviour and characteristics properties of gases.
(iii) Give the mathematical form of the Boyle’s law.
Answer:
(i) Charle’s law may be stated as volume of a given mass is directly proportional to its absolute temperature, if the pressure remains constant.
\(\frac{\mathrm{V}_{1}}{\mathrm{~T}_{1}}=\frac{\mathrm{V}_{2}}{\mathrm{~T}_{2}}=\mathrm{K} = K\) (at constant pressure)
Where V₁ is volume occupied by gas 1 at temperature T₁ and V₂ is volume occupied by gas 2 at temperature T₂.

(ii) Behaviour and characteristics properties of gases are as follows :

1. Gases have low density : The number of molecules per unit volume in a gas is very small as compared to solids and liquids. Gases have large inter molecular space between their molecules. Therefore they have low density.

2. Gases exert pressure in all directions : The moving particles of gas collide with each other and also in the container that is why they exert pressure in all directions.
\(\mathrm{V}_{1}=\frac{\mathrm{K}}{\mathrm{P}_{1}}\) (at constant temperature)
Or P₁V₁ = P₂V₂

(g) (i) Balance each of the following chemical equations given below :
1. KMnO₄ + H₂SO₄ → K₂SO₄ + MnSO₄ + H₂O + [O]
2. Al₂O₃ → Al + O₂
Answer:
1. 2KMnO₄ + 3H₂SO₄ → K₂SO₄ + 2MnSO₄ + 3H₂O + 5[O]
2. AIP3 → 4A1 + 3O₂

(ii) Identify the substance which matches the description given below :
(1) It catches fire and bums with a lilac-coloured flame and produces hydrogen when reacted with water.
(2) It acts as a dehydrating agent and removes water molecule from blue vitriol.
(3) The metals that cannot displace hydrogen from dilute hydrochloric acid.
Answer:
1. Potassium when reacts with water bums with a lilac coloured flame.
2K + 2H₂O → 2KOH + H₂

2. Conc. H₂SO₄ removes water molecules from blue vitriol and acts as a dehydrating agent.

3. Metals like Cu, Ag and Au.

(h) Match Column A with Column B.

Column A	Column B
(i) Alkaline earth metals	(A) Cone. H2SO4
(ii) Green house gases	(B) Argon, Neon, Helium
(iii) Dehydrating agent	(C) K, L, M, N, O, P, Q
(iv) Inert gases	(D) CO2, N2O
(v) Caustic soda	(E) NaOH

Answer:
(i) (C)
(ii) (D)
(iii) (A)
(iv) (B)
(v) (E)

Section – II
(Attempt any four questions from this Section)

Question 2.
(a) Consider M is any alkali metal. Give the general equation as well as explanation of the following :
(i) When M reacts with acids.
(ii) When M reacts with water.
(iii) When M reacts with air.
Answer:
(a) (i) Li, Na, K, Rb, Cs, Fr are all alkali metals.
When M reacts with acids the following action takes place.
2M + 2HCl → 2MCl + H₂
They react violently with dil. HCl and dil. H₂SO₄ to produce hydrogen.

(ii) When M reacts with water the following action takes place.
2M + 2H₂O → 2MOH + H₂

(iii) When M reacts with air the following action takes place.
4M + O₂ → 2MO
MO +H₂O → 2MOH
They react rapidly with oxygen and water vapour in the air.

(b) Write the balanced chemical equation of the following :
(i) Lead nitrate when heated.
(ii) Ammonium and hydrogen chloride combines.
(iii) Reaction of iron with chlorine.
Answer:
(i) \(2 \mathrm{~Pb}\left(\mathrm{NO}_{3}\right)_{2} \stackrel{\text { (Heät) }}{\longrightarrow} 2 \mathrm{PbO}+4 \mathrm{NO}_{2}+\mathrm{O}_{2}\)
Lead nitrate decomposes on heating leaving a yellow residue lead monoxide, brown
gas nitrogen dioxide and colourless gas oxygen.

(ii) Ammonium and hydrogen chloride both compounds combine to form a new
compound ammonium chloride.
NH₃(g) + HCl(g) → NH₄Cl(s)

(iii) When iron reacts with chlorine iron (Ill) chloride salt is formed.
2Fe + 3Cl₂→ 2FeCl₃

(c) Draw the orbit structure for each of the following compounds and also write their electronic configuration and valency.
(i) Boron
(ii) Neon
(iii) Fluorine
(iv) Hydrogen
Answer:

Question 3.
(i) Write two similarities between hydrogen and halogens.
(ii) How hydrogen is produced from cold water ?
Answer:
(i) Similarities between hydrogen and halogen are :

1. Hydrogen and halogen have one electron less than the nearest inert gas.
2. Both have valency 1, they accept 1 electron of the nearest inert gas to attain the electronic configuration.

(ii) Among the reactive metals sodium reacts with cold water and form their corresponding hydroxides evolving hydrogen. The reaction is exothermic and vigorous.
2Na + 2H₂O → 2NaOH + H₂

(b) (i) What is Newland’s law of octaves ?
(ii) Write two drawbacks of Newland’s law of octaves ?
(iii) Write two merits of Newland’s classification.
Answer:
(i) According to Newland’s law of octaves, “When elements are arranged by increasing atomic mass, the properties of every eighth element starting from any element are a repetition of the properties of the starting element”.

(ii) Drawbacks of Newland’s law of octaves are :
1. This classification did not work with heavier elements i.e., those lying beyond calcium. As more and more elements are discovered, they could not fit into Newland’s Law.
2. Iron which resembles, with cobalt and nickel in properties has been placed far away from those elements.

(iii) 1. It relates the properties of the elements to their atomic masses.
2. For the first time it is shown that there is a distinct periodicity in the properties of elements.

(c) Write the merits of the modem periodic table.
Answer:
Merits of the modem periodic table are as follows :
1. It is based on atomic number, which is an even better fundamental property compared to atomic mass.
2. Position of an element in the table is related to its electronic configuration.
3. It shows regular changes in properties of elements on moving across a period or down a group.
4. Modem periodic table is easier to remember, understand and reproduce.

Question 4.
(a) 120 cm³ of a gas is taken at 27.3 K. The temperature is then raised to 0°C. What is the new volume of the gas ? The temperature is kept constant.
Answer:

(b) Calculate the final volume of a gas ‘X’ if the pressure of the gas, originally at STP, is doubled and its temperature is made three times.
Answer:

(c) Calculate the relative molecular mass of each of the following :
(i) Ammonia (NH₃)
(ii) Tricalcium phosphate Ca₃(PO₄)₂
Answer:
(i) To find the molecular mass of NH₃, the first step is to look up the atomic masses of nitrogen and hydrogen.
Atomic mass of nitrogen = 14.0067 Atomic mass of hydrogen = 1.00794
Next, multiply the atomic mass of each atom by the number of atoms in the compound. There is one nitrogen atom (no subscript is given for one atom). There are three hydrogen atoms, as indicated by the subscript.
Molecular mass = (1.x 14.0067) + (3 x 1.00794)
Molecular mass = 14.0067 + 3.02382 = 17.0305

(ii) From the periodic table, the atomic masses of each element are :
Ca = 40.078 P = 30.973761
O = 15.9994
The tricky part is figuring out how many of each atom are present in the compound. There are three calcium atoms, two phosphorus atoms, and eight oxygen atoms.

To get the part of the compound which is in parentheses, multiply the subscript immediately following the element symbol by the subscript that closes the parentheses.
Molecular mass = (40.078 x 3) + (30.97361 x 2) + (15.9994 x 8)
Molecular mass = 120.234 + 61.94722 + 127.9952 = 310.17642 = 310.18

Question 5.
(i) Write the electronic configuration of the following :
(1) { }_{20}^{40} \mathrm{Ca}
(2) { }_{32}^{16} \mathrm{S}
(ii) What is an atom ?
(iii) What are protons ?
Answer:
(i) 1. Is² 2s² 2f 3s² 3p⁶ 4s²
2. Is² 2s² 2f 3s² 3p⁴

(ii) An atom is the smallest particle of an element that exhibits all the properties of that element. It may or may not exist independently but takes part in every chemical reaction.

(iii) Proton may by defined as a sub-atomic particle having mass 1 amu, e., equal to hydrogen atom and has unit positive charge.

(b) (i) What do you understand by the term Isobars ? Give examples.
(ii) What is a neutron ?
(iii) What is an atom ? Write its structural parts.
Answer:
(i) Isobars are atoms of different elements with the same mass number, but different atomic numbers. Since the properties of elements depend upon atomic number, so they have both different physical and chemical properties.
Examples : ⁴⁰S, ⁴⁰C1, ⁴⁰Ar, ⁴⁰K and ⁴⁰Ca. The nuclei of these nuclides all contain 40 nucleons; however, they contain varying numbers of protons and neutrons.

(ii) A neutron is a sub-atomic particle or fundamental particle of an atom with no charge and mass almost equal to the mass of proton e., hydrogen atom. Neutron is denoted by pn¹. The subscript 1 represents its mass and subscript 0 represents its electrical charge.

(iii) An atom is built up of a number of sub-atomic particles e., electrons, protons and neutrons. Electron has charge -1, proton has charge +1 and neutron has charge 0. There are two structural parts of an atom-the nucleus and orbits.

(c) How would you distinguish between the following pairs of substances on the basis of tests given in brackets ?
(i) Magnesium (Action of hot water and steam)
(ii) Zinc hydroxide (Action of bases and acids)
(iii) Unknown substance (Action of dilute sulphuric acid)
Answer:
(i) Magnesium reacts slowly with boiling water and forms a base, magnesium hydroxide liberating hydrogen.
Mg + 2H₂O → Mg(OH)₂ + H₂  ↑
Magnesium bums in steam with an intense white light, liberating hydrogen gas and white ash i.e., magnesium oxide.
Mg + H₂O → MgO + H₂ ↑

(ii) Hydroxides of zinc are amphoteric i.e., they react with both bases and acids to give salt and water.
ZnO + 2HCl → ZnCl₂ + H₂O
ZnO + 2NaOH → Na₂ZnO₂ + H₂O

(iii) When dilute sulphuric acid is added to the given unknown substance and then is warmed a colourless gas is evolved with brisk effervescence, and the gas on passing through lime water turns it milky.
Na₂CO_s + H₂SO₄ → Na₂SO₄ + H₂O + CO₂

Question 6.
(a) State whether the property increases, decreases or remains same in the following cases :
(i) Alkali metals reactivity when one moves down the group.
(ii) Atomic size of elements when one moves down a group.
(iii) Metallic character when one moves down a group.
Answer:
(a) (i) Alkali metals are all very reactive and degree of reactivity increases down the group.
Li < Na < K < Rb < Cs

(ii) Size of atoms of successive element increases down the group.
Li < Na < K < Rb < Cs
Atomic size increases

(iii) Metallic character increases as one moves down the group. For example : In group 15, nitrogen and phosphorus are non-metals, arsenic and antimony are metalloids and bismuth is a typical metal.

(b) (i) What is the difference between soft water and hard water ?
(ii) Write three physical properties of water.
Answer:
(i)

Soft water	Hard water
1. It readily forms lather with soap. 2. It contains high amount of sodium. 3. It is not harsh on skin.	1. It does not readily forms lather with soap. 2. It contains high amount of calcium and magnesium. 3. It is harsh on skin

Physical properties of water are :
1. Nature : Pure water is a clear, transparent liquid. It is colourless, odourless and tasteless.
2. Boiling point: Under normal pressure, pure water boils at 100°C. The boiling point of water is affected by pressure, the greater the pressure the higher the boiling point.
3. Freezing point : Pure water freezes at 0°C under pressure. The freezing decreases with increase in temperature.

(c) Write two types of chemical reactions with two examples of each.
Answer:
Two types of chemical reaction are as follows :

1. Direct combination reactions : A reaction in which two or more substances combine to form a single substance is called a combination reaction.
Example 1.
C + O₂ → CO₂ + Heat.
Carbon bums in oxygen to form a gaseous compound carbon dioxide.
Example 2.
Fe + S → FeS
The reaction between iron and sulphur to form iron (II) sulphide.

2. Displacement reactions : A reaction in which more reactive element displaces a less reactive element which result in the formation of its salt solution.
Example 1.
CuSO₄ + Zn → ZnSO₄ + Cu

When zinc is added to copper sulphate solution the displacement reaction takes place and blue colour of the solution fades and becomes colourless.
Example 2.
2KI + Cl₂  → 2KCl + H₂

When chlorine gas is passed through a solution of potassium iodide the colourless solution turns yellow brown as iodine appears.

Question 7.
(i) Complete the following table :

Element	Atomic	Mass no.	P	n	e
A	1	1	1	—	—
B	14	—	17	—	7
C	—	12	12	12	—
D	35	—	17	—	17

(ii) Give the electronic configuration of A, B, C and D.
(iii) Identify A, B, C and D.
(iv) How many valence electrons are present in A, B, C and D ?
(v) What is the valency of A, B, C and D ?
Answer:
(ii) Electronic configuration of A = 1 Electronic configuration of B = 2, 5 Electronic configuration of C = 2, 8, 2 Electronic configuration of D = 2, 8, 7
(iii) A = Hydrogen, B = Nitrogen, C = Magnesium, D = Chlorine
(iv) A = l, B = 5, C = 2, D = 7
(v) A = l, B = 3, C = 2, D = 1

(b) Write the electronic configuration of the following :
(i) Iron (Fe)
(ii) Palladium (Pd)
Answer:
(i) Electronic configuration of iron is :
Is² 2s² If 3s² 3f 3d⁶ 4s²
(ii) Electronic configuration of palladium is :
Is² 2s² 2 f 3s² 3p⁶ 3d¹⁰ 4s² 4 f 4d¹⁰

(c) State the valency of the element having :
(i) 5 electrons in the valence shell.
(ii) Electronic configuration 2, 5.
Answer:
(i) The valency of an element having 5 electrons in the valence shell is 3.
(ii) The valency of an element having 2, 5 electronic configuration is 3.
The valency of an element having 2, 5 electronic configuration is 3 and having 2, 3 electronic configuration is also 3.

ICSE Class 9 Chemistry Question Papers with Answers