List of top Physics Questions on Radioactivity

निम्नलिखित नाभिकीय अभिक्रिया पर विचार कीजिए: \[ ^{238}U \rightarrow ^{234}Th + ^4He \] $^{238}U$, $^{234}Th$ और $^{4}He$ के द्रव्यमान क्रमशः 238.050 u, 234.043 u और 4.003 u हैं। अभिक्रिया के लिए $Q$ का मान, keV में, है : \[ (दिया है : 1u = 931.5MeV/c^2) \]

The half-life of a certain radio isotope is $4$ minutes. The number of radioactive nuclei at a given instant is $10^6$. Then the number of radioactive nuclei left $2$ minutes later would be

The radioactivity of a certain radioactive element drops to 1/64 of its initial value in 30 sec. Its half-life is:

Two radioactive materials $A_1$ and $A_2$ have half-life periods 20 s and 10 s respectively. Initially a mixture of these materials contain 40 g of $A_1$ and 160 g of $A_2$. The time taken for $A_1$ and $A_2$ to become equal in the mixture is:

A nuclear reactor starts producing a radioactive nuclide $X$ from $t = 0$, at a constant rate of $\alpha$ per second. Each decay of $X$ produces energy $E_0$, which is utilized to heat a liquid of mass $m$ and specific heat $s$. Assuming no heat loss from the liquid and taking $\lambda$ as the decay constant of $X$, the rate of increase in the temperature of the liquid is:

The half-life of a radioactive substance is 10 days. The decay constant is

The half-life of a radioactive substance is $10$ days. The fraction of the original sample left after $30$ days is:

If a radioactive substance is reduced to $6.25%$ of its initial amount in $256$ days then its half-life period is

For beta-minus decay, which statement is TRUE?

Which radiation has maximum ionization power?

The half-life of a radioactive substance is 4 hours. If initially there are 256 grams, how much remains after 10 hours?

Two radioactive elements A and B initially have the same number of atoms. The half-life of A is the same as the average life of B. If $ \lambda_A $ and $ \lambda_B $ are the decay constants of A and B respectively, then choose the correct relation from the given options:

If a radioactive element with a half-life of 30 min undergoes beta decay. The fraction of the radioactive element that remains undecayed after 90 min is:

A radioactive nuclei X decays simultaneously to two nuclei Y and Z as:

t_½ is 12 minutes while t'_½ is 3 minutes. Find the time in which nuclei X decays 50%.

A radioactive element ${}^{242}_{92}X$ emits two $\alpha$-particles, one electron, and two positrons. The product nucleus is represented by ${}^{234}_{P}Y.$ The value of $P$ is _______.

A radio active material is reduced to 1/8 of its original amount in 3 days.
If 8×10^-3 kg of the material is left after 5 days the initial amount of the material is

A radioactive element of mass $1\ \text{kg}$ after $N$ years is left with only $125\ \text{g}$. If the half-life of the element is $12.5$ years, then the value of $N$ is

A radioactive substance has a half life of $10^8$ years and an activity of $10^4\ \text{Bq}$. The number of atoms of this substance present is:

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:

The activity of a radioactive material is 6.4 × 10^-4 curie. Its half life is 5 days. The activity will become 5 × 10^-6 curie after

How many alpha and beta particles are emitted when Uranium ₉₂U²³⁸ decays to lead₈₂Pb²⁰⁶

The half life of a radioactive substance is 5 years. After x years, a given sample of the radioactive substance gets reduced to 6.25% of its initial value. The value of x is ______.

A radioactive sample disintegrates via two independent decay processes having half lives T₁/₂\^{(1)} and T₁/₂\^{(2)} respectively. The effective half-life, T₁/₂ of the nuclei is :

For a radioactive material, half-life is 10 minutes. If initially there are 600 number of nuclei, the time taken (in minutes) for the disintegration of 450 nuclei is

When the light of frequency 2v₀ (where v₀ is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is v₁ . When the frequency of the incident radiation is increased to 5v₀ , the maximum velocity of electrons emitted from the same plate is v₂ . The ratio of v₁ to v₂ is