Nuclei practice · Medium

If mass of $U^{235}=235.12142 \mathrm{amu}$, mass of $\mathrm{U}^{236}=1.008665 \mathrm{amu}$, then the energy required to remove one neutron from the nucleus $\mathrm{U}^{236}$ is nearly about -

Nuclear fission experiments show that the neutrons split the uranium nuclei into two fragments of about same size. This process is accompanised by the emission of several

Atomic nuclei having same mass number but difference atomic numbers are called

Modern treatment method P.E.T. is besed on !

In nuclear fusion process, heat energy released is

An unstable element is produced in a nuclear reactor at a constant rate. If its half life is 100 years, how much time in years is required to produce $50 \%$ of the equilibrium quantity?

Calculate the disintegration energy Q for the fission of ${ ~}_{42}^{98} \mathrm{M}$ o into two equal fragments, ${ }_{21}^{49} \mathrm{~S} c$. If $Q$ turns out to be positive, explain why this process does not occur spontaneously. Given that :

$m\left({ }_{42}^{98} \mathrm{Mo}\right) =97.90541 \mathrm{~amu}$

$m\left({ }_{21}^{49} \mathrm{Sc}\right) =48.95002 \mathrm{~amu}$

$m_n =1.00867 \mathrm{~amu}$.

For the radioactive nuclei that undergo either $\alpha$ or $\beta$-decay, which one of the following cannot occur?

Two nucleons are at a separation of $\mathrm{1 }\,\mathrm{fm}$. The net force between them is ${\mathrm{F}_\mathrm{1}}$ if both neutrons, ${F_2}$ if both are protons, and ${F_3}$ if one is a proton and the other is a neutron.

Read the following statements:

(A) Volume of the nucleus is directly proportional to the mass number.

(B) Volume of the nucleus is independent of mass number.

(C) Density of the nucleus is directly proportional to the mass number.

(D) Density of the nucleus is directly proportional to the cube root of the mass number.

(E) Density of the nucleus is independent of the mass number.
Choose the correct option from the following options

${\mathbf{F}_{pe}}$ represents electrical force on proton due to electron and ${\mathbf{F}_{ep}}$ on electron due to proton in a hydrogen atom.Similarly ${\mathbf{F}_{pe}}$ represents the gravitational force on proton due to electron and ${\mathbf{F}_{ep}}$ the corresponding force on electron due to proton. Which of the following is not true?

The half-life period of a radioactive element X is same as the mean life time of another radioactive element Y. Initially both of them have the same number of atoms. Then

Which of the following has the mass closest in value to that of the positron
$1\,\,a.m.u = 931\,\,MeV$

The density of uranium is of the order of

Nuclear binding energy is equivalent to

Ionization power and penetration range of radioactive radiation increases in the order

The half-life of radium is 1600 years. After how many years $25 \%$ of a radium block remains undecayed?

A 280 days old radioactive substance shows an activity of 6000 dps, 140 days later it’s activity becomes 3000 dps. What was its initial activity.

The radius of germanium ($\mathrm{Ge}$) nuclide is measured to be twice the radius of ${}_4^9\mathrm{Be}$. The number of nucleons in $\mathrm{Ge}$ are

Average binding energy of a nucleon inside an atomic nucleus is about

Assertion: All natural radioactive elements are ultimately converted to lead.

Reason: All the elements above lead are unstable.

One Becquerel is defined as

In $\beta^{+}$emission what happens to upquarks

Choose the incorrect statement about the strong nuclear force.

Consider $\alpha - \mathrm{Particles},\,\,\mathrm{\beta } - \mathrm{Particles }\,\,\mathrm{and}\,\,\gamma - \mathrm{rays}$, each having an energy of $\mathrm{0}\mathrm{.5 }\,\mathrm{MeV}$. In increasing order of penetrating powers, the radiations are

A uranium reactor develops thermal energy at a rate of 300 MW. Calculate the amount of ${ }^{235} \mathrm{U}$ being consumed every second. Average energy released per fission is $200 \mathrm{~MeV}$.

A radioactive isotope $\mathrm{X}$ with a half-life of $1.37\,\, \times \,\,{10^9}$ years decays to $Y$ which is stable. A sample of rock from the moon was found to contain both the elements $X$ and $Y$ which were in the ratio $\mathrm{1:7}$. The age of the rock is

The half life period of radioactive nucleus is 12.5 hours and its mass is 256 gm. The time after which amount of remaining substance is 1gm will be...... hours

Which is the correct expression for half-life

For a nucleus ${ }_Z^A X$ having mass number ${A}$ and atomic number ${Z}$

A. The surface energy per nucleon $\left(b_s\right)=a_1 A^{2 / 3}$

B. The coulomb contribution to the binding energy $b_c=-a_2 \frac{Z(Z-1)}{A^{4 / 3}}$

C. The volume energy $b_v=a_3 A$

D. Decrease in the binding energy is proportional surface area.

E. While estimating the surface energy, it is assumed that each nucleon interacts with 12 nucleons,
( $a_1, a_2$ and $a_3$ are constants)

Choose the most appropriate answer form the options given below;