Question

100 mL of $PH_3$ on decomposition produced phosphorus and hydrogen. The change in volume is

• A. 50 mL increase
• B. 500 mL decrease
• C. 900 mL decrease
• D. nil

Answer 1

Answer: (A)

50 mL increase

Answer 2

$\underset{\text{2 vol}}{ {2PH_{3}}} \to \underset{\text{3 vol}}{ {3H_{2}}}+2P$ $2$ vol of $PH_{3}$ give $3$ vol of $H_{2}$ $\therefore 100\,mL$ of $PH_{3}$ gives $150\,mL$ of $H_{2}$ $\therefore$ Increase in volume $=150\,mL-100\,mL$ $=50\,mL$