Nuclei practice · Medium

The decay constant of a radioactive element, which disintegrates to 20 grams from 40 grams in 100 minutes is

Two radioactive substances A and B have decay constant $5\lambda \;$ and $\lambda$ respectively. At t = 0 they have the same number of active nuclei. The ratio of number of active nuclei of A to those of B will be $2\left( {1/{e^2}} \right)$ after a time interval

Assertion: The magnetism of the magnet is due to the spin motion of electron.

Reason: The dipole moment of electron is smaller than that due to orbit motion around nucleus.

A radioactive material has a half life of $\mathrm{10}\,\,\mathrm{days}$. What fraction of the material would remain after $\mathrm{30}\,\,\mathrm{days}$

Calculate no. of fissions of $U^{235}$ required per $\mathrm{sec}$ to generate power of $10 \mathrm{~KW}$.

In a radioactive material the activity at time ${t_1}$ is ${R_1}$ and at a later time ${t_2}$, it is ${R_2}$. If the decay constant of the material is $\lambda$ , then

Hydrogen bomb is based upon

Light energy emitted by stars is due to

$1\,\,g$ of hydrogen is converted into $0.993\,\,g$ of helium in a thermonuclear reaction. The energy released is

In any fission process, the ratio of
$\frac{{{\text{mass}}\,{\text{of}}\,{\text{fission}}\,{\text{products}}}}{{{\text{mass}}\,{\text{of}}\,{\text{parent}}\,{\text{nucleus}}}}$ is

Energy generation in stars is mainly due to

The $\beta$-particles of a radioactive metal originate from

The particle emitted in the decay of ${ }_{92}^{238} \mathrm{U}$ to ${ }_{92}^{234} \mathrm{U}$

Assertion (A): Two different radioactive substances have initially same number of nuclei. Their decay constants are $\lambda_{1}$ and $\lambda_2\left( < \lambda_1\right)$, then initially first radioactive substance decays at faster rate.
Reason (R): Half-life of first radioactive substance is more.

Protons and neutrons are built out of

Assertion: Heavy water preferred over ordinary water as a moderator in reactors.
Reason: Heavy water, used for slowing down the neutrons, has lesser absorption probability of neutrons than ordinary water.

In a mean life of a radioactive sample

A radioactive nucleus can decay simultaneously by two different processes which have decay constant ${\lambda _1}\,\,\mathrm{and}\,\,{\lambda _2}$.The effective decay constant of the nuclide is $\lambda ,$ where

Half life of radioactive element depends upon

The exchange particles responsible for nuclear weak interaction are

Outside a nucleus

The correct order of ionizing capacity of $\alpha ,\beta$ and $\gamma -$ rays is

The binding energy per nucleon for deuteron and helium are $\mathrm{1}\mathrm{.1}\,\,\mathrm{MeV}$ and $\mathrm{7}\mathrm{.0}\,\,\mathrm{MeV}$. The energy released when two deuterons fuse to form a helium nucleus is

As compound $^{12}C$ atom, $^{14}C$ atom has

The radius of the ${}_2He^4$ nucleus is 3 fermi. The radius of ${}_{82}Pb^{206}$ nucleus will be

Select the true statement from the following. Nuclear force is

What is approximately the ratio of nuclear radii of gold isotope $_{79}^{238}Au$ and silver isotope $_{47}^{108}Ag$.

The particle $A$ is converted into $C$, $via$ following reaction.
$A \to B{ + _2}\mathrm{H}{\mathrm{e}^4}$
$B \to C\,\, + \,\,2{e^ - }$

The mass of radium (mass number 226, half-life 1600 years) with an activity of one curie is almost?

The energy released in the explosion of an atom bomb is mainly due to