Q. The decomposition of phosphine ($PH_3$) on tungsten at low pressure is a first-order reaction. It is because the
A) rate is proportional to the surface coverage
B) rate is inversely proportional to the surface coverage
C) rate is independent of the surface coverage
D) rate of decomposition is very slow
Explanation
[Solution] At low pressure, surface coverage is proportional to $PH_3$ pressure, and rate is proportional to surface coverage, giving first-order kinetics. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.