Question

Two radioactive materials X ${}_1$and X${}_2$ have decay constants 10$\lambda$ and $\lambda$ respectively. If finally they have the same number of nuclei, then the ratio of the number of nuclei of X ${}_1$ to that of X${}_2$ will be 1/e after a time

• A. $\frac{1}{10\lambda }$
• B. $\frac{1}{11\lambda }$
• C. $\frac{11}{10\lambda }$
• D. $\frac{1}{9\lambda }$

Answer 1

Answer: (D)

Note:- time is not given when both have same no of nuclei