Question

Three-fourths of the active nuclei present in a radioactive sample decay in 3/4 s. The half-life of the sample is –

• A. 1 s
• B. 1/2 s
• C. 3/4 s
• D. 3/8 s

Answer 1

Answer: (D)

3/8 s

Answer 2

$\frac { \mathrm { N } } { \mathrm { N } _ { 0 } } = \frac { 1 } { 4 } = \left( \frac { 1 } { 2 } \right) ^ { 2 } = \left( \frac { 1 } { 2 } \right) ^ { \frac { 3 / 4 } { \mathrm {~T} } }$2T =