Question

28. Change in volume when 100 mL PH, decomposed
to solid phosphorus and H, gas.
(1) Increase in 50 mL
(2) Decrease in 50 mL
(3) Increase in 150 mL
(4) Decrease in 200 ml​

Answer 1

Increase in volume = (150-100) ml = 50 ml. (The volume of solid phosphorus is negligible). Decomposition of phosphine on heating gives solid phosphorus and hydrogen gas. Thus, 100 ml of PH2 => 100×3/2=150 ml of H2.