Question

The half life period catalytic decomposition of $A{B}_3$ at 50 mm is found to be 4 hours and at 100 mm it is 2 hours. The order of reaction is:

• A. 1
• B. 2
• C. 3
• D. zero

Answer 1

Answer: (B)

2

When initial pressure of $A{B}_3=50mm$

$t_{1/2}=4hr$

When initial pressure of $A{B}_3=100mm$

$t_{1/2}=4hr$

It means when concentration is doubled, half life is halved. So, it is a second reaction.

As we know,

For second order reaction: $t_{1/2}\propto (a{)}^{-1}$