Question

For an elementary reaction $X\left(g\right)\to Y\left(g\right)+Z\left(g\right)$, the half-life period is $10$ min. In what period would the concentration of $X$ be reduced to $10\%$ of original concentration?

• A. $20$Min
• B. $33$Min
• C. $15$Min
• D. $25$Min

Answer 1

Answer: (B)

$33$Min

It is a 1st Order Reaction.

$t_{1/2}$ = $\frac{0.693}{k}$

$10$ = $\frac{0.693}{k}$

$k=0.0693{min}^{-1}$

$t=\frac{2.303}{0.0693}log\frac{100}{10}$

$t=33min$

Hence, the correct option is $B$