Question

Four different experiments were conducted in the following ways-

I) $3g$ of carbon was burnt in $8g$ of oxygen to give $11g$ of $C{O}_2$.

II) $1.2g$ of carbon was burnt in air to give $4.2g$ of $C{O}_2$.

III) $4.5g$ of carbon was burnt in enough air to give $11g$ of $C{O}_2$.

IV) $4g$ of carbon was burnt in oxygen to form $30.3g$ of $C{O}_2$.

Law of constant proportions is illustrated in which of the following experiment(s)?

• A. I and III only
• B. II and III only
• C. IV only
• D. I only

Answer 1

The correct option is D I only

The law of definite proportion or law of constant composition states that a given chemical compound always contains its component elements in a fixed ratio (by mass) and does not depend on its source and method of preparation.

In the option, $A$, $3g$ of carbon reacts with $8g$ of oxygen to form $11g$ of carbon dioxide.

$C+O_2\stackrel{}{\to }C{O}_{2\left(g\right)}$

$3+8=11$

Thus, it follows the law of constant proportion. Option $D$ is correct.