NCERT EXAMPLER CLASS 9 SCIENCE CHAPTER 3-ATOMS AND MOLECULES

Multiple Choice Questions

 1. Which of the following correctly represents 360 g of water?

(i) 2 moles of H20

(ii) 20 moles of water

(iii) 6.022 × 10^23 molecules of water

(iv) 1.2044×10^25 molecules of water

(a) (i) 

(b) (i) and (iv)

(c) (ii) and (iii)

 (d) (ii) and (iv)

2. Which of the following statements is not true about an atom?

(a) Atoms are not able to exist independently

(b) Atoms are the basic units from which molecules and ions are formed

(c) Atoms are always neutral in nature

(d) Atoms aggregate in large numbers to form the matter that we can see,

feel or touch

3. The chemical symbol for nitrogen gas is

(a) Ni 

(b) N2 

(c) N+

 (d) N

4. The chemical symbol for sodium is

(a) So

 (b) Sd

 (c) NA

 (d) Na

5. Which of the following would weigh the highest?

(a) 0.2 mole of sucrose (C12 H22 O11)

(b) 2 moles of CO2

(c) 2 moles of CaCO3

(d) 10 moles of H2O

6. Which of the following has maximum number of atoms?

(a) 18g of H2O

(b) 18g of O2

(c) 18g of CO2

(d) 18g of CH4

7. Which of the following contains maximum number of molecules?

(a) 1g CO2

(b) 1g N2

(c) 1g H2

(d) 1g CH4

8. 3.42 g of sucrose are dissolved in 18g of water in a beaker. The number of oxygen atoms in the solution are

(a) 6.68 × 10^23

(b) 6.09 × 10^22

(c) 6.022 × 10^23

(d) 6.022 × 10^21

9. Which of the following correctly represents 360 g of water? A change in the physical state can be brought about

(a) only when energy is given to the system

(b) only when energy is taken out from the system

(c) when energy is either given to, or taken out from the system

(d) without any energy change