Nuclei practice · Mixed difficulty

Assertion: For nuclear reactor, it is desirable to have $K=1$.

Reason: Sustained chain reaction occur at this critical condition.

During the $\mathrm{\beta } - \mathrm{decay}$

The velocity of alpha particles from polonium (atomic weight 210) is $1.6 \times 10^7 \mathrm{~m} / \mathrm{sec}$. What is the velocity of recoil atoms?

Pick out the correct statement from the following.

The mass of $\alpha$-particle is

An element of mass $\mathrm{M}$ has $\mathrm{Z}$ protons and $\mathrm{N}$ neutrons. Masses of proton and neutron are $m_p$ and $m_n$ respectively. Choose the correct relation among following options

Uranium -238 decays to Thorium -234 with half-life $5 \times 10^9 \mathrm{yr}$. The resulting nucleus is in the excited state and hence further emits $\gamma$-rays to come to the ground state. It emits $20 \gamma$-rays per second. The emission rate will drop to $5 \gamma$-rays per second in

Heavy water is the best _____ in nuclear reactor.

$\alpha -$ particle consists of:

The radioactive decay of uranium into thorium is expressed by the equation $_{92}^{238}U \to _{90}^{234}Th\,\, + \,X$, where $'X'$ is

The penetrating power of $\alpha$-rays is

The operation of a nuclear reactor is said to be critical, if the multiplication factor $\left( k \right)$ has a value

Tritium is an isotope of hydrogen whose nucleus triton contains 2 neutrons and 1 proton. Free neutrons decay into $p+e^{-}+\bar{v}$. If one of the neutrons in triton decays, it would transform into ${He}^3$ nucleus. This does not happen. This is because

A nuclear bomb exploded $200\,\,km$ above the surface of moon. The sound of explosion on the moon

A nucleus is bombarded with a high speed neutron so that resulting nucleus is a radioactive one. This phenomenon is called

A nucleus of uranium decays at rest into nuclei of thorium and helium. Then:

When a radioactive substance emits an $\alpha$-particle, its position in the periodic table is lowered by

In ${\mathrm{\beta }^ + }$ decay process, the following changes take place inside the nucleus

Choose the suitable condition in order to carry out the nuclear reaction

${ }_1 \mathrm{H}^1+{ }_1 \mathrm{H}^1+{ }_1 \mathrm{H}^2={ }_2 \mathrm{H}^4+{ }_1 \mathrm{e}^0+\text { energy }$

A nuclear reactor delivers a power of $10^9 {~W}$. What is the amount of fuel consumed by the reactor in one hour?

In an experiment, the activity of 1.2 milligrams of radioactive potassium chloride (chloride of isotope $\mathrm{K}-40$ ) was found to be $170 \mathrm{~s}^{-1}$. Taking molar mass of to be $0.075 \mathrm{~kg} \mathrm{~mole}^{-1}$, find the number of $K-40$ atoms in the same and hence find the half-life of K-40. Avogadros' number $=6.0 \times 10^{23}$ mole $^{-1}$.

The ratio of molecular mass of two radioactive substances is $\mathrm{3/2}$ and the ratio of their decay constants is $\mathrm{4/3}$. Then, the ratio of their initial activity per mole will be

Mean life of neutron is about

Calculate the radius of $\mathrm{Ge}^{70}$. Given $R_0=1.1 \mathrm{~fm}$

In a fission process, nucleus $A$ divides into two nuclei $B$ and $C$, their binding energies being ${E_a},{E_b}$ and ${E_c}$ respectively. Then

A radioactive sample has $6.0 \times 10^{18}$ active nuclei at a certain instant. How many of these nuclei will still be in the same active state after two half-lives?

The mass number of $He$ is $\mathrm{4}$ and that for sulphur is $\mathrm{32}$. The radius of sulphur nucleus is larger than that of helium, by times

${O}_2$ molecule consists of two oxygen atoms. In the molecule, nuclear force between the nuclei of the two atoms

A heavy nucleus $\mathrm{X}$ of mass number 240 and binding energy per nucleon $7.6 \mathrm{~MeV}$ is split into two fragments $\mathrm{Y}$ and $\mathrm{Z}$ of mass numbers 110 and 130. The binding energy of nucleons in $\mathrm{Y}$ and $\mathrm{Z}$ is 8.5 $\mathrm{MeV}$ per nucleon. Calculate the energy $\mathrm{Q}$ released per fission in $\mathrm{MeV}$

The volume of a nucleus is directly proportional to
(where $A =$ mass number of the nucleus)