Assignment No – 2
Some Basic Concepts of
Chemistry
Que 1. What is unit factor method? Express the
following in SI units - 93 million miles (distance between earth and sun)
Que 2. What do mean by gram atomic mass. one
million silver atoms weigh 1.79 x 1016 g. Calculate the gram atomic
mass of silver.
Que 3. Copper oxide obtained by heating copper
carbonate or copper nitrate contains copper and oxygen in the same ration by
mass. Which law is illustrated by this observation? State the law.
Que 4. Write the empirical formula of the
following:
(a) N2O4 (b) C6H12O6
(c) H2O (d) H2O2
Que 5. Chlorine has two isotopes of atomic mass
units 34.97 and 36.97. The relative abundance of the isotopes is 0.755 and
0.245 respectively. Find the average atomic mass of chlorine.
Que 6. How are 0.50 mol Na2CO3
and 0.50 M Na2CO3 different?
Que 7. What is the percentage of carbon,
hydrogen and oxygen in ethanol?
Que 8. What do mean by molarity. Calculate the
molarity of NaOH in the solution
prepared by dissolving its 4 g in enough water
to form 250 mL of the solution.
Que 9. Express the following in the scientific
notation with 2 significant figures-
(a) 0.0048 (b) 234,000 (c) 200.0
Que 10. Calculate the number of atoms in each
of the following:
(i) 52 moles of Ar (ii) 52 u of He (iii) 52 g of He
Que 11. What is the difference between
empirical and molecular formula? A compound contains 4.07 % hydrogen, 24.27 %
carbon and 71.65 % chlorine. Its molar mass is 98.96 g. What are its empirical
and molecular formulas?
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