class -9 atoms and molecules

Class – IX Subject -Science Atoms and molecules 

Time 1 hr          M.M.30 

(Section A) 10 x 1 = 10 

1. The atomic radius of hydrogen atom is 

a. 0.037 nm b. 0.037 x 10 -9 m  c. both a &b   d. none 

2. Complete the following sentence: In water, the proportion of hydrogen and oxygen is ---------- by mass

a. 1:8 b. 3:4 c. 9:0 d. none 

3. The actual mass of hydrogen atom 

a. 1.673 x 10 ^-24 g b. 1.673 x 10 c.1u d. both a & b 

4. The symbol of cobalt a.C.o. b. CO c. Co. d. none 

5. Atomicity of noble gases is one 

a. True b. false c. can’t say d none 

6. The molecular mass of sulfuric acid 

a. 28 u b. 108 u c. 98u d. none 

7. What are the number of electron and proton in chlorine ion 

a. 17p & 18 e b. 18 p & 17 e c. 17 e & 0 e d. none 

8. The value of symbol ‘N’ a. 6.022 x 10²³ b. 6.022 x 10^-23 c. 0.622 x 10²³ d. none 

9. What is the mass of of 0.2 moles of oxygen atoms? 

a. 2.3 g b. 3.2 g c. .32 g d. none 

10. Write the atomicity of CO₂ gas a. 2 b. 3 c. 0 d. none 

(Section B) 10 X 1 = 10

1.what is meant by saying “the atomic mass of oxygen is 16? 

2. What is the significance of formula H₂O? 

3. Calculate the formula mass of calcium chloride and sodium carbonate 

4. An element Z forms an oxide ZO₃. What is the valency of Z? 

5. Write the Latin names of sodium, iron, mercury and tin. 

6. Define 1 u. 

7. Define electro negativity of any atom. 

8. Name the element represent by the following symbols Hg, Pb, Au, Ag and Sn 

9. Write down the atomicity of carbon dioxide, oxygen, ozone, solid sulphur. 

10. Write down the atomicity of carbon dioxide, oxygen, ozone, solid sulphur. 

(Section C) 3 x 2 = 6 

1. Write down the atomicity of carbon dioxide, oxygen, ozone, solid sulphur. 

2. Give major draw –backs of Dalton’s atomic theory of matter. 

3. Work out the formula of magnesium chloride. 

(Section D) 2 x 2.5 = 5 

6. State the law of conservation of mass. Give one example also. 

7. In an experiment, 1.288 g of copper oxide was obtained from 1.03 g of copper. In anotherexperiment 3.672 g of copper oxide obtain from the 2.938 g of copper. Show that thesefigures verify the law of constant proportion