Question

A zero-order reaction, $A\to$ Product, with an initial concentration ${\left[A\right]}_0$ has a half-life of $0.2s$. If one starts with the concentration $2{\left[A\right]}_0$, then the half-life is:

• A. $0.1s$
• B. $0.4s$
• C. $0.2s$
• D. $0.8s$

Answer 1

The correct option is B $0.4s$

For zero-order reaction, half-life is $\frac{[A{]}_0}{2k}$

"or"

$k=\frac{[A{]}_0}{2t_{1/2}}=\frac{[A{]}_0}{0.4}$

If initial concentration is $2[A{]}_0$ then,

$t_{1/2}=\frac{2[A{]}_0}{2\times \frac{[A{]}_0}{0.4}}=0.4sec$