Question

At $500\text{K}$, the half - life period of a gaseous reaction at the initial pressure of $80\text{kPa}$ is $350\text{sec}$. When the pressure becomes $40\text{kPa}$, the half-life period is $175\text{sec}$. The order of the reaction is:

• A. Zero
• B. One
• C. Two
• D. Half

Answer 1

The correct option is A Zero

When the initial pressure is halved, the half - life period is also halved. This shows that $t_{\frac{1}{2}}\propto$ initial pressure. This is so for reactions of zero order.