Question

Certain radioactive substance reduces to 25% of its value in 16 days. Its half-life is-

• A. 32 days
• B. 32 days
• C. 64 days
• D. 28 days

Answer 1

Answer: (B)

32 days

Answer 2

A.P. = 25% = $\frac { 1 } { 4 }$ = \ n = No. of half life = 2

\ t = nT_1/2 ̃ T_1/2 = $\frac { \mathrm { t } } { \mathrm { n } }$ = $\frac { 16 } { 2 }$ = 8 days