Nuclei practice · Medium

Given below are two statements: one is labelled as
Assertion A and the other is labelled as Reason R

Assertion A : The binding energy per nucleon is
practically independent of the atomic number for
nuclei of mass number in the range 30 to 170.

Reason R : Nuclear force is short ranged.

In the light of the above statements, choose the
correct answer from the options given below

In half life of a radio isotope is $\mathrm{2}\,\,\mathrm{seconds}$ and number of atoms are only $\mathrm{4}$, then after one half life remaining (without decay) atoms are probably

Assertion: Radioactive nuclei emit $\beta^{-1}$ particles.
Reason: Electrons exist inside the nucleus.

A count rate metre shows a count of $\mathrm{240}$ per minute from a given radioactive source later the metre shows a count rate 0f $30\,\,{\min ^{ - 1}}$⁡ . The half-life of the source is

In a reactor, 2kg of $_{92}{U^{235}}$ fuel is fully used up in 30 days. The energy released per fission is 200 MeV.
Given that, the Avogadro number, $N = 6.023 \times {10^{26}}{K^{ - 1}}\,mo{l^{ - 1}}$ and $1\,\,eV = 1.6 \times {10^{ - 19}}J.$ The power output of the reactor is close to

At a specific instant emission of radioactive compound is deflected in a magnetic field. The compound cannot emit

$\pi$ mesons can be

The half -life period of a radioactive substance is 20 days. What is the time taken for $(7 / 8)^{\text {th }}$ of its original mass to disintegrate?

Our bodies are mostly made of hydrogen $(\mathrm{Z}=1)$, carbon $(Z=6)$, and oxygen $(Z=8)$. In our bodies, are there many more neutrons than protons, many fewer neutrons than protons, or are there about the same number of each?

A radio active material is reduced to $1 / 8$ of its original amount in 3 days. If $8 \times 10^{-3} \, \mathrm{kg}$ of the material is left after 5 days the initial amount of the material is

If the nuclear force between two protons, two neutrons and between proton and neutron is denoted by $\mathrm{F}_{\mathrm{pp}}, \mathrm{F}_{\mathrm{nn}}$ and $\mathrm{F}_{\mathrm{pn}}$ respectively, then

Assertion : Size of nucleus is constant in electron scattering or gamma scattering.

Reason : Electron scattering or gamma scattering is controlled by distribution of charge in
nucleus.

Natural water contains a small amount of tritium $\left({ }_1^3 \mathrm{H}\right)$. This isotope beta-decays with a half-life of 12.5 years. A mountaineer while climbing towards a difficult peak finds debris of some earlier unsuccessful attempt. Among other things he finds a sealed bottle of whisky. On return he analyses the whisky and finds that it contains only 1.5 per cent of the ${ }_1^3 \mathrm{H}$ radioactivity as compared to a recently purchased bottle marked '8 years old'. Estimate the time of that unsuccessful attempt.

${U^{238}}$ decays into $T{h^{234}}$ by the emission of an $\alpha -$ particle. There follows a chain of further radioactive decays, either by $\alpha -$ decay or by $\beta -$ decay. Eventually a stable nuclide is reached and after that, no further radioactive decay is possible. Which of the following stable nuclides is the end product of the ${U^{238}}$ radioactive decay chain

For the stability of any nucleus

During a nuclear fusion reaction

For maintaining sustained chain reaction, the following is required

If a proton and anti-proton come close to each other and annihilate, how much energy will be released

The rate of disintegration of fixed quantity of a radioactive element can be increased by

The phenomenon of pair production is-

Number of neutrons in a gold nucleus with A = 197 and Z = 79 is

Assertion: In He-Ne laser, population inversion takes place between energy level of neon atoms.

Reason: Helium atom has a metastable energy level.

Fusion reactions take place at high temperature because

An accident in a nuclear laboratory resulted in depostion of a certain amount of radioactive material of half - life 18 days inside the laboratory. Tests revealed that the radiation was 64 times more than the permissible level required for safe operation of the laboratory. What is the minimum number of days after which the laboratory can be considered safe for use?

Identify the pair of physical quantities that have same dimensions:

If $50 \%$ of energy released during fission would be converted into electrical energy, then number of fissions in a second in a nuclear reactor of 6.4 $MW$ output is (Energy per fission is $200 \,{MeV}$ )

The half life of a radioactive substance is $\mathrm{T}$. The time taken, for disintegrating $\frac{7}{8}$ th part of its original mass will be:

A radioactive nucleus $A$ finally transforms into a stable nucleus $B$. Then $A$ and $B$ can be

In which radioactive disintegration, neutron dissociates into proton and electron

In the nuclear decay given below:

${ }_{\mathrm{Z}}^{\mathrm{A}} \mathrm{X} \longrightarrow{ }_{\mathrm{Z}+1}^{\mathrm{A}}\mathrm{Y} \longrightarrow{ }_{\mathrm{Z}-1}^{\mathrm{A}-4} \mathrm{~B}^* \longrightarrow{ }_{\mathrm{Z}-1}^{\mathrm{A}-4} \mathrm{~B} \text {, }$

the particles emitted in the sequence are