Question

A radioctive sample decays `7/8` times its original quantity in 15 minutes. The half-life of the sample is ______.

Options

• 5 min

• 7.5 min

• 15 min

• 30 min

Answer 1

A radioctive sample decays `7/8` times its original quantity in 15 minutes. The half-life of the sample is 5 min.

Explanation:

Remaining = `1/8`

So \[\ce{N_0->[15min]\frac{N_0}{8}=\frac{N_0}{2^3}}\]

So, 3t_1/2 = 15 min ⇒ t_1/2 = 5 min