MCQ PRACTICE

Welcome to your Ncert - class 9- science -Chapter 3 – Atoms and Molecules 1

Choose the correct answer from the options given below.

In water, the hydrogen-to-oxygen mass ratio is:

1:32

1:16

1:64

1:8

None

If we assume that one-sixth the mass of an atom of (\12_{C}\) isotope is taken as the reference, the mass of one molecule of oxygen will:

be double its original value

increase by four fold

be the same

be half its original value

None

Which of the following cations does not form soluble complex with excess NaOH solution as well as excess NH4 OH solution ?

$$Cu^{+2}$$

$$Al^{+3}$$

None of these

$$Fe^{+3}$$

None

The average relative atomic mass of chlorine is 35.45. It consists of two naturally occurring isotopes chlorine-35 and chlorine-37. What is the fractional abundance of chlorine-37?

0.2200

0.3550

0.4500

0.3650

None

The number of gold atoms in 300 mg of a gold ring of 20-carat gold (Au=197: pure gold is 24 carat) is:

$$9.5 \times 10^{20}$$

$$7.6 \times 10^{20}$$

$$4.5\times 10^{20}$$

$$6.8 \times 10^{15}$$

None

Which of the following statements is correct about the reaction given below?
$$4Fe(s)+3O2(g) \rightarrow 2Fe_{2}O_{3}(g)$$

The total mass of reactants = = Total mass of the products. Therefore, the law of multiple proportions is followed.

The total mass of reactants = = Total mass of the products. It follows the law of conservation of mass.

Amount of Fe2 O3 can be increased by taking any one of the reactants (iron or oxygen) in excess.

Amount of Fe2O3produced will decrease if the amount of any one of the reactants (iron or oxygen) is taken in excess.

None

What is the ratio of the number of atoms of elements potassium, chlorine, and oxygen respectively present in

245g of KClO 3?

1:1:3

39:36:48

2:2:3

1:2:6

None

Hydrogen combines with oxygen to form

H2O in which 16 g of oxygen combine with 2 g of hydrogen. Hydrogen also combines with carbon to form CH4 in which 2 g of hydrogen combine with 6 g of carbon.If carbon and oxygen combine together then they will do show in the ratio of

12 : 24

1 : 2

6 : 16

13 : 32

None

Number of atoms in 560 g of Fe (atomic mass = 56 u) is

None of these

Equal to that of 70 g N

Twice that of 70 g N

Half that of 20 g H

None

10.

Which among the following is true about one mole of a gas?

It can occupy any volume at S.T.P.

It always occupies a fixed volume at N.T.P.

It always occupies 2 litres.

It always occupies 1 litre.

None

11.

A charged particle formed by the loss or gain of electrons during a compound formation is called an .....

ion

Cation

Anion

Positron

None

12.

On heating KClO3 at a certain temperature, it is observed that one mole of

KClO3 yields one mole of O2. What is the mole fraction of KClO 4 in the final solid mixture containing only

KCl and KClO 4, the latter being formed by the parallel reaction?

0.67

0.50

0.25

0.75

None

13.

The average molecular mass of a mixture of gas containing nitrogen and carbon dioxide is 36. The mixture contains 280 g of nitrogen. Therefore, the amount of CO2 present in the mixture is :

44 g

880 g

4.4 g

440 g

None

14.

Of two oxides of iron, the first contained

22% and the second contained

30% of oxygen by weight. The ratio of weights of iron in the two oxides that combine with the same weight of oxygen is

1:1

1:2

2:1

3:2

None

15.

In a chemical scale, the relative mass of the isotopic mixture of oxygen atoms

$(16_{o}, 17_{o}, 18_{o})$ is assumed to be equal to

11.00

16.002

17.00

16.00

None

16.

Which of the following is a suitable example for illustrating the law of conservation of mass?

(Atomic mass of O = 16 g/mol, H = 1 g/mole)

18g of water is completely converted into vapour state on heating.

18g Of water freezes at 4 degree C to give same mass of ice.

18g of water in liquid state is obtained by heating 18 g of ice.

18 g of water is formed by the combination of 16 16 g oxygen with 2 g of hydrogen.

None

17.

1.375 g of cupric oxide was reduced by heating in a current of hydrogen and the weight of copper obtained was

1.098

1.098 g. In another experiment,

1.156

1.156 g of copper was dissolved in nitric acid and the resulting solution was evaporated to dryness. The residue of copper nitrate when strongly heated was converted into

1.4476

1.4476 g of cupric oxide. State the law illustrated by these chemical combinations.

Law of reciprocal proportion

None of these

Law of multiple proportion

Law of constant composition

None

18.

Two gaseous samples of the same compound were analyzed. One contained 1.2 g of carbon and 3.2 g of oxygen. The other contained 27.3% carbon and 72.7% of oxygen. The experimental data follows:

Law of reciprocal proportion

Law of conservation of mass

Law of multiple proportion

Law of definite proportion

None

19.

How many molecules are present in one gram of hydrogen $ H_{2} $

$$3.0125\times10^{-13}$$

$$3.01 \times10^{23}$$

$$6.023\times10^{23}$$

$$6.023\times10^{22}$$

None

20.

Which of the following substance is made up of only one type of particle?

mixture

element

mixed metal

compound

None

Chapter 1 Matter In Our Surroundings

Chapter 2 – Is Matter Around Us Pure

Chapter 3 – Atoms and Molecules

Chapter 4 – Structure of the Atom

Curriculum

Ncert Class9-Chemistry-Science

Chapter 1 Matter In Our Surroundings

Chapter 2 – Is Matter Around Us Pure

Chapter 3 – Atoms and Molecules

Chapter 4 – Structure of the Atom

MCQ PRACTICE – 1