Question

A radioactive substance contains 10000 nuclei and its half-life period is 20 days. The number of nuclei present at the end of 10 days is –

• A. 7070
• B. 9000
• C. 8000
• D. 7500

Answer 1

Answer: (A)

7070

Answer 2

$\frac { \mathrm { N } } { \mathrm { N } _ { 0 } }$ = $\frac { 1 } { 2 ^ { n } }$ Ž $\frac { \mathrm { N } } { 10000 }$ = $\frac { 1 } { 2 ^ { \frac { 10 } { 20 } } }$ Ž N = 7070