CLASS: IX NCERT (CBSE)

Chemistry

Atoms and Molecules

Question 1: In water, hydrogen and oxygen are present in the ratio of ________.

1. 1:8

2. 2:12

3. 2:3

4. 1:2

Answer: 1

Question 2: An example of a triatomic molecule is ___________.

1. Ozone

2. Nitrogen

3. Carbon monoxide

4. Hydrogen

Answer: 1

Question 3: The quantity of matter present in an object is called its _________.

1. Mass

2. Volume

3. Density

4. Vapour pressure

Answer: 1

Question 4: Indivisibility of an atom was proposed by ___________.

1. Dalton

2. Rutherford

3. Thomson

4. Bohr

Answer: 1

Question 5: The value of Avogadro constant is ___________.

1. 6.022 x 1024

2. 6.022 x 1022

3. 60.22 x 1023

4. 6.022 x 1023

Answer: 4

Question 6: All samples of carbon dioxide contain carbon and oxygen in the mass ratio of 3:8.This is in agreement with the Law of ___________.

1. Conservation of Mass

2. Constant Proportion

3. Multiple Proportion

4. Reciprocal Proportion

Answer: 2

Question 7: The atomic mass of sodium is 23. The number of moles in 46g of sodium is ________.

1. 2

2. 1

3. 4

4. 0

Answer: 1

Question 8: The molecular formula of potassium nitrate is ________.

1. KNO

2. KNO3

3. KNO2

4. KON

Answer: 2

Question 9: Kalium is the Latin name of ________.

1. Potassium

2. Krypton

3. Calcium

4. Phosphorus

Answer: 1

Question 10: The smallest particle of a substance that is capable of independent existence is _________.

1. Atom

2. Molecule

3. Electron

4. Proton

Answer: 2

Question 11:

1. Atomic number

2. Atomic mass

3. Atomic mass scale

4. Number of electrons

Answer: 2

Question 12:

1. 1.25

2. 15

3. 14

4. 12

Answer: 2

Question 13: The molecular mass of ammonia is _________.

1. 17 grams

2. 31 grams

3. 20 grams

4. 25 grams

Answer: 1

Question 14: Atomic mass of calcium is 40. The mass of 2.5 gram atoms of calcium is _______.

1. 40 g

2. 2.5 g

3. 100 g

4. 80 g

Answer: 3

Question 15: The number of atoms in a molecule of the elementary substance is called ________.

1. Atomic number

2. Avogadro number

3. Atomic mass

4. Atomicity

Answer: 4

Question 16: Avogadro number represents the number of atoms in ________.

1. 12 grams of 12C

2. 320 grams of sulphur

3. 32 grams of oxygen

4. 1 gram of 12C

Answer: 1

Question 17: The number of moles in 5 grams of calcium is _________.

1. 0.125 mole

2. 5 mole

3. 1.25 mole

4. 12.5 moles

Answer: 1

Question 18: 2 molecules of nitrogen are represented by ________.

1. N

2. 2N2

3. N2

4. 2N

Answer: 2

Question 19: One mole of H2O corresponds to

1. 22.4 litre at 1 atm and 250C

2. 6.02 x 1023 atoms of hydrogen and 6.02 x 1023 atoms of oxygen

3. 18 g

4. 1 g

Answer: 3

Question 20: The number of molecules in 4.25 g of ammonia is approximately

1. 1.0 x 1023

2. 1.5 x 1023

3. 2.0 x 1023

4. 3.5 x 1023

Answer: 2

Question 21: A sample contains 22 g of carbon dioxide. This is equal to

1. One molar volume of carbon dioxide

2. One mole of carbon dioxide

3. Half mole of carbon dioxide

4. Two moles of carbon dioxide

Answer: 3