List of top Physics Questions on Half life

The half-life of a radioactive substance is 20 minutes. $\frac{1}{3}$rd part of substance has decayed in time $t_1$ and $\frac{2}{3}$rd part of it has decayed in time $t_2$. Then, ($t_2 - t_1$) is nearly

Activity of a radioactive sample decreases to $\left(\dfrac{1}{4}\right)^{th}$ of its original value in 4 days. Then in 16 days its activity will become $x$ times the original value. The value of $x$ is

A radioactive sample has half-life of \(5\) years. The percentage of fraction decayed in \(10\) years will be

Two samples A and B contain equal amount of radioactive substances. If \((\frac{1}{8})^{th}\) of sample A and \((\frac{1}{128})^{th}\) of sample B, remain after 9 hours, then the ratio of half life period of B to that of A is

The half-life of the isotope \(_{11}\text{Na}^{24}\) is 15 hr. How much time does it take for \((\frac{7}{8})^{\text{th}}\) of a sample of this isotope to decay ?

If decay constant of a radioactive element doubles, then its half-life time becomes:

A freshly prepared radioactive source of half life 2 hours 30 minutes emits radiation which is 64 times the permissible safe level. The minimum time, after which it would be possible to work safely with source, will be _______ hours.

Following statements related to radioactivity are given below:
(A) Radioactivity is a random and spontaneous process and is dependent on physical and chemical conditions.
(B) The number of un-decayed nuclei in the radioactive sample decays exponentially with time.
(C) Slope of the graph of log_e (no. of undecayed nuclei) Vs. time represents the reciprocal of mean life time (τ).
(D) Product of decay constant (λ) and half-life time (T_1/2) is not constant.
Choose the most appropriate answer from the options given below: