List of top Physics Questions on Nuclei

Two lighter nuclei combine to from a comparatively heavier nucleus by the relation given below: \(^2_1X+^2_1X=^4_2Y\). The binding energies per nucleon for, \(^2_1X\) and \(^4_2Y\) are 1.1 MeV and 7.6 MeV respectively. The energy released in the process is ______ MeV.

A radioactive nucleus can decay by two different processes. Half-life for the first process is 3.0 hours while it is 4.5 hours for the second process. The effective half-life of the nucleus will be:

The disintegration rate of a certain radioactive sample at any instant is $4250$ disintegrations per minute $10$ minutes later, the rate becomes $2250 $ disintegrations per minute The approximate decay constant is : (Take $\log _{10} 188=0274$ )

A nucleus with mass number 240 breaks into two fragments each of mass number 120, the binding energy per nucleon of unfragmented nuclei is 7.6 MeV while that of fragments is 8.5 MeV. The total gain in the Binding Energy in the process is

Given the masses of various atomic particles $m _{ p }=1.0072 u$ , $m _{ n }=1.0087 \,u$ $m _{ e }=0.000548 u$ , $m _{\overline{ v }}=0$, $m _{ d }=2.0141 u$ where $p \equiv$ proton, $n \equiv$ neutron, $e \equiv$ electron, $\overline{ v } \equiv$ antineutrino and $d \equiv$ deuteron. Which of the following process is allowed by momentum and energy conservation ?

Find the binding energy per nucleon for ${ }_{50}^{120} Sn$. Mass of proton $m _{ p }=1.00783\, U ,$ mass of neutron $m_{n}=1.00867 \,U$ and mass of tin nucleus $m _{ Sn }=119.902199 \,U $ (take $1U = 931 \,MeV)$

A radioactive nucleus decays by two different processes. The half life for the first process is $10 s$ and that for the second is $100 s$. the effective half life of the nucleus is close to:

The activity of a radioactive sample falls from $700\, s^{-1}$ to $500\, s^{-1}$ in 30 minutes. Its half life is close to :

In a radioactive material, fraction of active material remaining after time $t$ is $9 / 16 .$ The fraction that was remaining after $t / 2$ is :

When a uranium isotope $^{235}_92 U$ is bombarded with a neutron, it generates $^{89}_{36} Kr$, three neutrons and :

A radio-active elements has half-life of $15$ years. What is the fraction that will decay in $30$ years?

Condiser the nuclear fission ${Ne^{20} -> 2 He^{4} + C^{12}} $ Given that the binding energy/nucleon of ${Ne^{20}, He^{4}}$ and ${C^{12}}$ are, respectively, 8.03 MeV, 7.07 MeV and 7.86 MeV, identify the correct statement :

Two radioactive materials $A$ and $B$ have decay constants $10 \lambda$ and $\lambda$, respectively. It initially they have the same number of nuclei, then the ratio of the number of nuclei of $A$ to that of $B$ will be $1/e$ after a time :

The ratio of mass densities of nuclei of $^{40}C_a$ and $^{16}O$ is close to :-

A sample of radioactive material $A$, that has an activity of $10 \; mCi (1 \; Ci = 3.7 \times 10^{10}$ decays/s), has twice the number of nuclei as another sample of a different radioactive maternal $B$ which has an activity of $20\, mCi$. The correct choices for hall-lives of $A$ and $B$ would then be respectively :

In a radioactive decay chain, the initial nucleus is $^{232}_{90}Th$ . At the end there are $6 \alpha$-particles and $4 \beta$-particles which are emitted. If the end nucleus, If $^{A}_{Z} X$ , $A$ and $Z$ are given by :

The energy of a hydrogen atom in the ground state is \(-13.6 eV.\) The energy of \(He^+\) ion in the first excited state will be

Which one of the following nuclei has shorter mean life?

Most common isotope of hydrogen (Non radioactive):

In a radioactive sample, $^{40}_{19} K$ nuclei either decay into stable $^{40}_{20} Ca$ nuclei with decay constant $4.5 \times 10^{-10}$ per year or into stable $^{40}_{18}\, Ar$ nuclei with decay constant $0.5 \times 10^{-10}$ per year. Given that in this sample all the stable $^{40}_{20}Ca$ and $^{40}_{18}$ $Ar$ nuclei are produced by the $^{40}_{19}K$ nuclei only. In time $t \times 10^{9}$ years, if the ratio of the sum of stable $^{40}_{20}\,Ca$ and $^{40}_{18}\, Ar$ nuclei to the radioactive $^{40}_{19}\, K$ nuclei is $99$, the value of t will be : [Given $ln\, 10\, =\, 2.3$]

A solution containing active cobalt $^{60}_{27}Co$ having activity of $0.8 \, \mu Ci$ and decay constant $\lambda$ is injected in an animal?s body. If $1 \, cm^3$ of blood is drawn from the animal?s body after 10 hrs of injection, the activity found was 300 decays per minute. What is the volume of blood that is flowing in the body ? ($1 \, Ci=3.7 \times 10^{10}$ decays per second and at $t=10 hrs e^{- \lambda t} =0.84$)

An unstable heavy nucleus at rest breaks into two nuclei which move away with velocities in the ratio of $8 : 27$. The ratio of the radii of the nuclei (assumed to be spherical) 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

An atomic power nuclear reactor can deliver 300 MW. The energy released due to fission of each nucleus of uranium atoms \(U^{238}\) is 170 MeV. The number of uranium atoms fissioned per hour will be

Which one of the following is not emitted by radioactive elements ?