Question

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

• A. 3
• B. 1
• C. 2
• D. 0

Answer 1

The correct option is C 2

For second order reaction, the expression for the half life period is $t_{\frac{1}{2}}=\frac{1}{K}\frac{1}{a)}$
Thus the half life period is inversely proportional to the concentration for a second order reaction.
When concentration is doubled from 50 mm to 100 mm, the half life period is reduced to half from 4 hours to 2 hours.