Question

Two oxides of a certain metal were separately heated in a current of hydrogen until constant weights were obtained. The water produced in each case was carefully collected and weighed. 2 g of each oxide gave, respectively 0.2517 g and 0.4526 g of water. This observation illustrates

• A. law of conservation of mass
• B. law of constant proportions
• C. law of multiple proportions
• D. law of reciprocal proportions

Answer 1

Answer: (C)

Weight of $H_{2}O$ from oxides give weight of oxygen and metal in oxide.
$0.2517g{H}_{2}O$ contains oxygen $=\frac{16}{18}\times 0.2517=0.2237g$
Mass of metal $=2-0.2237=1.7763g$
$0.4526g{H}_{2}O$ contains oxygen $=\frac{16}{18}\times 0.4526=0.4023g$
Mass of metal $=2-0.4023=1.5977g$
Thus, we can get the weight of oxygen with constant weight of metal
$(1g)$ for other oxides, which two are in simple ratio of
$0.125:0.251=1:2$