ICSE Class 9 Chemistry Sample Question Paper 2 with Answers

ICSE Class 9 Chemistry Sample Question Paper 2 with Answers

Section -1
(Attempt all questions from this section)

Question 1.
(a) Fill in the blanks with the correct choice given in brackets.
(i) The atomic number of an element is the number of ………………. and electrons present in the nucleus of an atom. [protons/negative charge]
(ii) As one moves down a group, size of atoms of successive elements ……………………….. [increases/ decrease
(iii) When zinc reacts with dilute sulphuric acid………………………… gas is evolved. [carbon dioxide/hydrogen]
(iv) Anode rays are made up of …………………. charged particles, [positively/negatively]
(v) Elements which have 4 or 5 or 6 or 7 electrons in their outermost shell are ……………………..
Answer:
(i) Proton
(ii) Increases
(iii) Hydrogen
(iv) Positively
(v) Non-metal

(b) Choose the correct answer from the options given below :
(i) The ozone layer protects us from the sun’s harmful. rays.
(A) UV rays
(B) X rays
(C) Gamma rays
(D) Beta rays
Answer:
(A) UV Rays

(ii) The three elements calcuium, strontium and barium have the following similarities :
(A) All are metals
(B) Each has an oxide that is alkaline in nature
(C) Each has valency 2
(D) All of the above
Answer:
(D) All of the above

(iii) The specific value of latent heat of vaporization of water is :
(A) 2286 J/g
(B) 540 cal/g
(C) 336 J/g
(D) Both A and B
Answer:
(D) Both A and B

(iv) The gas that turns lime water milky is :
(A) Carbon dioxide
(B) Oxygen
(C) Hydrogen
(D) Nitrogen
Answer:
(A) Carbon dioxide

(v) Gases exert pressure in :
(A) One direction
(B) All directions
(C) Two directions
(D) None of the above
Answer:
(B) All directions

(c) Name the gas evolved in each of the following cases :
(i) When an electric current is passed through accumulated water.
(ii) Copper carbonate is heated strongly.
(iii) Nitrogen combines with hydrogen.
(iv) When mercuric oxide is heated.
(v) Addition of sodium to cold water.
Answer:
(i) Hydrogen and oxygen
(ii) Carbon dioxide
(iii) Ammonia
(iv) Mercury and oxygen
(v) Hydrogen.

(d) Give a reason for each of the following :
(i) Why Water is an excellent liquid to use in cooling systems ?
(ii) A solution is always clear and transparent.
(iii) Lakes and rivers do not suddenly freeze in the winters.
(iv) A solute cannot be separated from a solution by filtration.
(v) Fused CaCl₂ or cone. H₂SO₄ is used in desiccators.
Answer:
(i) Water is an excellent liquid to use in cooling systems because of its ability to absorb large quantities of heat as a cooling agent.

(ii) A water-soluble solid disappears in a solution where the solvent is water, and water has the property of being clear and transparent. So, the solution is also always clear and transparent.

(iii) Lakes and rivers do not freeze suddenly in winters because of the high specific latent heat of solidification, i.e., the amount of heat released when 1 g of water solidifies to from 1 g of ice at 0°C. It is about 336 J/g or 80 cal/g.

(iv) The component which dissolves in a solvent is known as a solute. So, it can be separated from a solution by the filtration process. However, the filtration process is applicable only when the solute is insoluble in the solution. So, the solute cannot be separated from the solution by filtration.

(v) Anhydrous calcium chloride or cone. H₂SO₄ is a drying agent that can readily absorb moisture from other substances without chemically reacting with them. So, it is used in desiccators.

(e) What do you observe when :
(i) Mercuric chloride and potassium iodide is rubbed.
(ii) Ammonia reacts with oxygen.
(iii) A solution of silver nitrate is kept in sunlight.
(iv) Lead sulphide is heated.
(v) Barium chloride is added to dilute sulphuric acid.
Answer:
(i) They give a scarlet coloured substance called mercuric iodide.
(ii) It produces nitric oxide and water vapour in the presence of a catalyst.
(iii) It decomposes in the presence of sunlight and releases oxygen gas.
(iv) It reacts with oxygen to form white lead sulphate.
(v) A thick white precipitate is formed.

(f) (i) State Boyle’s law.
(ii) What is the significance of Boyle’s law ?
(iii) Convert the temperature of 45°C to the Kelvin scale.
Answer:
(i) Boyle’s law states that volume of a given mass of a dry gas is inversely proportional to its pressure at constant temperature.
Mathematical expression of this law is :
Suppose a gas occupies volume V₁ when its pressure is P₁: then
\(\mathrm{V}_{1}=\frac{1}{\mathrm{P}_{1}} \text { or } \mathrm{V}_{1}=\frac{\mathrm{K}}{\mathrm{P}_{1}}\)
P₁V₁ = K = constant

If V₂ is the volume occupied when its pressure is P₂ : then
\(\mathrm{V}_{2}=\frac{1}{\mathrm{P}_{2}} \text { or } \mathrm{V}_{2}=\frac{\mathrm{K}}{\mathrm{P}_{2}}\)
Or     P₂V₂ = K = constant
P₁V₁ = P₂V₂ = K at constant temperature

(ii) On increasing pressure, volume decreases. The gas becomes denser. Thus at constant temperature, the density of a gas is directly proportional to its pressure. Atmospheric pressure is low at high altitudes, so air is less dense; hence, a lesser quantity of oxygen is available for breathing. This is the reason why mountaineers have to carry oxygen cylinders with them.

(iii) Temperature on Celsius scale = 45°C
from the formula
T (in °C) + 273.15 = T (in K)
45 + 273.15 = T (in K)
T = 318.15 K

(g) (i) Balance the chemical equations given below :
1. Cl₂ + KBr → 2KCl + Br
2. 2KClO → 2KCl + O₂

(ii) Identify the substance which matches the description given below :
1. A nitrate which produces oxygen as the only gas.
2. A compound which produces carbon dioxide on heating.
3. An element which does not contain neutron.

(h) Match Column A with Column B.

Column A	Column B
(i) Hydrogen	(A) Magnesium chloride
(ii) Ionic bond	(B) Nitrogen family
(iii) Group 15	(C) Anions
(iv) Negative ions	(D) Boyle’s law
(v) P1V1 = P2V2	(E) Has 3 isotopes

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

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

Question 2.
(a) A metal exists as a liquid at room temperature is obtained by heating its sulphide ore in the presence of air.
(i) Name the metal and write its chemical symbol.
(ii) Write the name and formula of its sulphide ore.
(iii) Name a common device in which the metal is used.
Answer:
(i) Mercury (Hg)
(ii) Name of sulphide ore : Cinnabar, formula : HgS
(iii) Thermometer

(b) Write balanced chemical equations for each of the following
(i) Reaction of lime with water.
(ii) Reaction of copper sulphate solution with iron metal.
(iii) Addition of zinc to aqueous solution of copper sulphate.
Answer:
(i) When lime is reacted with water, it reacts vigorously and forms calcium hydroxide.
CaO + H₂O → Ca (OH)₂

(ii) When a piece of iron metal is placed in the copper sulphate solution then iron sulphate solution and copper metal are formed.
CuSO₄ + Fe → FeSO₄ + Cu

(iii) When zinc metal is placed in copper sulphate solution, then zinc sulphate solution and copper are obtained.
CuSO₄ + Zn → ZnSO₄ + Cu

(c) Draw the orbit structure for each of the following :
(i) Isotopes of carbon with mass number 12
(ii) Magnesium
Answer:
(i) Isotopes of Carbon with mass number 12

Question 3.
(a) (i) Write a short note on hydrogen.
(ii) Write physical properties of hydrogen.
(iii) Write those properties of hydrogen which differ from those of alkali metals and halogens ?
Answer:
(i) Hydrogen is the first element in the periodic table. Its atomic number is 1, and it has only one electron in ifs valence shell. Therefore, it belongs to the first group and first period in the periodic table.

(ii) Physical properties of hydrogen are :
(a) It is colorless, odourless and tasteless.
(b) Non-toxic in nature.
(c) Liquefies at below -240°C under pressure of about 20 atmosphere.

(iii) 1. Hydrogen atom has only one shell but alkali metals and halogens have two or more shells.
2. Oxides of hydrogen, H₂O is a neutral oxide. Oxides of halogens like Cl₂O, Cl₂O₇ are acidic in nature, while oxides of alkali metals like Na₂O, K₂O are basic in nature.

(b) (i) What is meant by periodicity of properties ?
(ii) Why are the elements of group 17 called halogens ?
(iiii) Elements of which group are called the noble gases ?
Answer:
(i) Repetition of properties after a certain interval is called periodicity of properties.
(ii) The elements of group 17 are called halogens because the elements of this group form salts with group 1 elements and the name halogen is derived from the Greek halogen which means salt former.
(iii) Elements of group 18 are called noble gases.

(c) (i) How do we classify the elements ?
(ii) In Mendeleev’s periodic table, why was there no mention of noble gases like helium, neon and argon ?
(iii) Arrange the following elements in the increasing order of atomic sizes :
Li, Na, Cs, Rb, Fr, K
Answer:
(i) We classify the elements according to their properties so that we can have an orderly arrangement of elements and may study such a large number of elements comfortably.
(ii) Mendeleev believed that certain more elements existed but were not discovered till that time. Hence, he left some gaps in his periodic table so that these gaps would be filled later after the discovery of elements.
(iii) Li < Na < K < Rb < Cs < Fr

Question 4.
(a) A given mass of a gas occupies 572 cm³ at 13°C and 725 mm Hg pressure. What will be its volume at 24°C and 792 mm Hg pressure ?
(b) Write the Gas Equation e., pressure, volume and temperature relationship.
(c) Calculate the relative molecular mass of each of the following :
(i) H₂O
(ii) Methanol
Answer:
(a) P₁ = 725 mm of Hg, V, = 572 cm³, = (273 + 13) K = 286 K, P₂ = 792 mm Hg, V₂ = ? cm³
T₂ = (273 + 24) K = 297 K.
Applying the gas equation,

The required volume of the gas is 543.75 cm³.

(b) If both pressure and temperature of a fixed mass of a gas are varied, a combination of Boyle’s law and Charle’s law gives us a fixed relation amongst its volume, pressure and temperature.
According to Boyle’s law
\(\mathrm{V}=\frac{\mathrm{K}}{\mathrm{P}}\)

Now, on combining the two laws, volume of a given mass of a gas varies inversely with pressure and directly with absolute temperature.
\(\frac{\mathrm{PV}}{\mathrm{T}}=\text { Constant }\)

Accordingly, if the volume of a given mass of a gas changes from V₁ to V₂, its pressure from P₁ to P₂ and its temperature from T₁ to T₂ then
\(\frac{P_{1} V_{1}}{T_{1}}=\frac{P_{2} V_{2}}{T_{2}} \)
The above mathematical expression is called gas equation.

(c) (i) The molecular mass of water, H₂O
= (2 x Atomic mass of hydrogen) + (1 x Atomic mass of oxygen)
= [2(1.0084 u) + 1 (16.00 u)] = 2.016 u + 16.00 u = 18.016 = 18.02 amu

(ii) The molecular mass of Methanol i.e., CH₃OH is
= (atomic mass of C) + (3 x atomic mass of H) + (atomic mass of O) + (atomic mass of H)
= (12 + 3 x 1 + 16 + 1) = 32 a.m.u.

Question 5.
(a) Elements of the periodic table with atomic numbers from 3 to 18 are shown in the table below. Some elements are shown by letters even though the letters are not the usual symbols of the elements.

3	4	5	6	7	8	9	10
A	B	C	D	E	F	G	H
11	12	13	14	15	16	17	18
I	J	K	L	M	N	O	P

Which of these is ?
(i) A noble gas
(ii) A halogen
(iii) An alkali metal
(iv) An element with valency 4
Answer:
(i) H and P are noble gases.
(ii) G and O are halogens.
(iii) A and I are alkali metals.
(iv) D and L have valency 4.

(b) Write the electronic configuration of the following :
(i) Indium (In)
(ii) Titanium (Ti)
Answer:
(i) Is² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p¹
(ii) Is² 2s² 2p⁶ 3s² 3p⁶ 3d² 4s²

(c) Write down in detail the defects of Mendeleev’s periodic table.
Answer:
The defects in Mendeleev’s periodic table are as follows :
1. Anomalous pairs : Argon with atomic mass 39.9 precedes potassium with atomic mass 39.1. Cobalt with atomic mass 58.9 precedes nickel with atomic mass 58.6. Tellurium with atomic mass 127.6 precedes iodine with atomic mass 126.9.

2. Position of isotopes : According to Mendeleev’s periodic law, isotopes of an element must be given separate places in the periodic table. Although they have different atomic masses but they were not assigned separate places.

3. Grouping of chemically dissimilar elements : Elements such as copper and silver bear no resemblance to alkali metals (lithium, sodium etc.) but they have been placed together in the first row.

4. Separation of chemically similar elements : Elements those are chemically similar, such as gold and platinum have been placed in separate groups.

5. Electron arrangement : It does not explain the electron arrangement of elements.

Question 6.
(a) Write three factors affecting solubility.
(b) What is Soft water and Hard water and also describes the types of hardness?
(c) Classify each of the following reactions as synthesis, decomposition, displacement or double decomposition :
(i) 2CO(g) + O₂ → 2CO₂(g)
(ii) \(2 \mathrm{HgO}(\mathrm{s}) \stackrel{\text { (heat) }}{\longrightarrow} 2 \mathrm{Hg}(\mathrm{l})+\mathrm{O}_{2}(\mathrm{~g})\)
(iii) CuSO₄ + Zn → ZnSO₄ + Cu↓
(iv) BaCl₂ + Na₂SO₄ → BaSO₄ + 2NaCl
Answer:
(a) The rate of dissolution of a solid in a liquid depends on the following factors :
1. Size of solute particles : The smaller the size of the solute particle, the greater is its total surface area exposed to the solvent. Therefore, the greater is the solubility of that solute.
2. Stirring : This brings more of the solvent in contact with the solute and thus
increases the rate of formation of solution.
3. Temperature : The solubility of a gas in a liquid always decreases with rise in temperature.

(b) Water is said to be soft if it readily forms lather with soap. Pure water or water containing sodium salts easily gives lather with soap. Such water is called soft water.
Hard water contains bicarbonates, chlorides or sulphates of calcium or magnesium that is why it does not readily form lather with soap.
There are two types of Hardness :
1. Permanent Hardness : This type of hardness cannot be removed by boiling.
2. Temporary Hardness : It is due to the presence of bicarbonates of calcium and magnesium. It can be easily removed by boiling.

(c) (i) Synthesis reaction : Where two substances combine to form a single substance. In
the above reaction, carbon monoxide, a compound bums in the presence of oxygen to form a single product named carbon dioxide.

(ii) Decomposition reaction : Where breaking up of compound into simpler compounds takes place. In the above reaction, the compound mercuric oxide when heated decomposes to form 2 element mercury and oxygen.

(iii) Displacement reaction : Where a more reactive element displaces a less reactive element. In the above reaction, when pieces of zinc are added to copper sulphate solution, the blue colour of the solution fades and becomes colourless and at the same time reddish brown particles of copper settle down in the beaker.

(iv) Double displacement reaction : Where two compounds react to form two new compounds by mutual exchange of radicals. This is an example of precipitation reaction in which two compounds in their aqueous state react to form an insoluble salt.

Question 7.
(i) Who discovered atom and write the main postulates of Dalton’s atomic theory ?
(ii) What do you mean by orbits and nucleus ?
(iii) What are valence electrons ?
Answer:
(i) The Greek philosopher Democritus called the parmanu an “atom”, which means “indivisibles”. But the first scientific theory about the structure of matter was given by “John Dalton”.
Main postulates of Dalton’s atomic theory are :
1. Matter consists of very small and indivisible particles called atoms.
2. Atoms can neither be created nor destroyed.
3. Atoms of an element combine in small number to form molecules.
4. Atoms are the smallest unit of matter that can take part in chemical reaction.
5. The atoms of an element are alike in all respects but they differ from the atoms of other elements.
6. Atoms of one element combine with atoms of another element to form molecules of a compound.

(ii) Orbits : It is the imaginary path where electrons revolve around the nucleus of an atom.
Nucleus : The protons and neutrons collectively called nucleons are found in the central part or nucleus of the atom.

(iii) The outermost shell of an atom is known as valence shell and the electrons present in the valence shell are known as valence electrons.

ICSE Class 9 Chemistry Question Papers with Answers