Question

In a particular reaction, the time required to complete half of the reaction was found to increase $9$ times when the initial concentration of reactant was reduced to one third.

What is the order of reaction?

• A. Zero
• B. First
• C. Second
• D. Third

Answer 1

The correct option is D Third

For Zero Order reaction :

$t_{\frac{1}{2}}=\frac{a_0}{2k}$

$\therefore$increasing $a_0$ increases $t_{\frac{1}{2}}$ (not zero order) rather for $3^{rd}$ order.

$t_{\frac{1}{2}}=\frac{3}{2k{a}_0^2}$

$\therefore$ decreasing $a_0$ by 3 times will increase $t_{\frac{1}{2}}$ by 9 times.