The half-life of a zero order reaction $\mathrm{A} \rightarrow$ products, is 0.5 hour. The initial concentration of A is $4 \mathrm{~mol} \mathrm{~L}^{-1}$. How much time (in hr ) does it take for its concentration to come from $2.0 \mathrm{~mol} \mathrm{~L}^{-1}$ to $1.0 \mathrm{~mol} \mathrm{~L}^{-1} ?$

• Correct answer
  A

  $\frac{1}{4}$
• B

  $\frac{1}{8}$
• C

  $\frac{1}{2}$
• D

  $\frac{1}{6}$

Hence, the correct answer is option: 'A'.