Question

76. A radioactive substance has 10^8 nuclei. Its half
life is 30 s. The number of nuclei left after 15 S
is nearly
(1) 2 x 10^5
12) 3 x 10^6
(3) 7x 10^7
(4) 5 x 10^8
​

Answer 1

Answer:

The answer is 3) 7 × 10⁷

at 15 s  

amount of nuclei = initial amount / $\sqrt{2}$

so the answer is ≅ 7 ×$10^{7}$