Question

The count rate of activity of a radioactive sample of a very large population decreased from 1024 to 128 in 3 minutes. Then the rate of disintegration at the end of 5 minutes is-

• A. 96
• B. 64
• C. 48
• D. 32

Answer 1

Answer: (D)

32

Answer 2

Ž T = 1 min

A¢ = A₀ $\left( \frac { 1 } { 2 } \right) ^ { \frac { 5 } { 1 } }$ = $\frac { \mathrm { A } _ { 0 } } { 32 } = \frac { 1024 } { 32 } = 32$