Question

In a radioactive substance at t = 0, the number of atoms is 8 × 10⁴. Its half life period is 3 years. The number of atoms 1 × 10⁴ will remain after interval-

• A. 9 years
• B. 8 years
• C. 6 years
• D. 24 years

Answer 1

Answer: (A)

9 years

Answer 2

t = 0, N₀ = 8 × 10⁴

N = 1 × 10⁴ ̃ t = ?

T_1/2 = 3year

\ A.P = = $\frac { 1 \times 10 ^ { 4 } } { 8 \times 10 ^ { 4 } }$ = $\frac { 1 } { 8 }$ = (\ n = 3)

\ t = n T_1/2 ̃ t = 3 × 3 = 9 year