Page 1 - 2. PRACTICE WORKSHEET

SAI International School
Subject-Chemistry

Ch-Atoms and molecules
Topic-Mind map and introduction, Laws of Chemical Combinations,
Dalton's atomic theory and its drawbacks

Practice Worksheet
MCQs
Q.1 A sample of pure water, irrespective of its source contains 11.1% hydrogen and
88.9% oxygen. The data supports
(a) law of constant proportions
(b) law of conservation of mass
(c) law of reciprocal proportions
(d) law of multiple proportions
Q.2 A chemical equation is always balanced to fulfil the condition of

(a) Dalton’s atomic theory

(b) law of constant composition

(c) law of multiple proportions

(d) law of conservation of mass

Q.3Identify the correct statements.
I.In a compound such as water, the ratio of the mass of hydrogen to the mass of oxygen
is always 8 : 1.

II.If 9 g of water is decomposed, 1 g of hydrogen and 8 g of oxygen are always

obtained.
III.In ammonia, nitrogen and hydrogen are always present in the ratio 14 : 3 by mass.

IV.Many compounds are composed of two or more elements and each such compound
has the same elements in the same proportions.

(a) I and III (b) I, II and III
(c) II and IV (d) All of these
Q.4If 1.4g of calcium oxide is formed by the complete decomposition of calcium
carbonate, then the amount of calcium carbonate taken and the amount of carbon
dioxide formed will be respectively:
a) 2.2 g and 1.1 g
b) 1.1 g and 2.5 g
c) 2.5 g and 1.1 g
d) 5.0 g and 1.1 g