$A$ and $B$ are two radioactive substances. The half-life of $A$ is same as the average life of $B$. The decay constant of $B$ is 3.33 per day. (assume $\ln 2=0.70$ )

• A

  If initially $A$ and $B$ have the same number of nuclei, then the ratio of the number of nuclei of $A$ to that of $B$ will be $1 / e$ after 1 day.
• Correct answer
  B

  If the initial amount of $A$ and $B$ are the same, then the ratio of the number of nuclei of $A$ to that of $B$ will grow exponentially.
• Correct answer
  C

  If the initial amount of $B$ is twice that of $A$, then the number of nuclei of $A$ and $B$ will be the same after 0.7 days.
• D

  $85.7 \%$ of $A$ will disintegrate in about 3 days.

Hence, the correct answer is options: 'B', 'C'.