**JEE Advanced 2019 Paper 1, Question 4**

In a radioactive sample, nuclei decay into stable nuclei with decay constant per year or into stable nuclei with decay constant per year. In this sample all the stable and nuclei are produced by the nuclei only. In time years, if the ratio of the sum of stable and nuclei to the radioactive nuclei is 99, the value of will be [Given ],

- 1.15
- 9.2
- 2.3
- 4.6

**Solution**

Let us first consider the situation where a sample of nuclei decays into a *single* type of nuclei . The number of nuclei changes with …