Question

Radon (Ra) decays into Polonium (Po) by emitting an a-particle with half-life of 4 days. A sample includes 6.4 x 1010 atoms of An After 12 days, how many
atoms of Rn will be left in the sample?
0
0.63 x 1010
0.8 x 1010
2.1x 1010
3.2 x 1010
​

Answer 1

Answer:

B.0. 8 ×1010 follow me on Insta : iamdevrajpurohit

Answer 2

Given:

The half life of Radon, t1/2 = 4 days

No of atoms, N = 6.4 x 10¹⁰

Total time, T = 12 days

To Find:

The no of atoms of Radon left in the sample after 12 days.

Calculation:

- The no of half lives in total time, n = 12 / 4 = 3

- No of atoms left after 3 half lives = N x (1 / 2ⁿ)

⇒ No of atoms left = 6.4 x 10¹⁰ x (1 / 2³)

⇒ No of atoms left = 0.8 x 10¹⁰

- So, the correct answer is (b) 0.8 x 10¹⁰.