In one \(\alpha-\)$$ and \(2\beta-\)$emissions:$

1.	mass number reduced by \(2\)
2.	mass number reduces by \(6\)
3.	atomic number is reduced by \(2\)
4.	atomic number remains unchanged

Which of the following is used as a moderator in nuclear reactors? 

1. Plutonium 

2. Cadmium 

3. Heavy water

4. Uranium 

Heavy water is used as a moderator in a nuclear reactor. The function of the moderator is 

1. to control energy released in the reactor

2. to absorb neutrons and stop the chain reaction

3. to cool the reactor

4. to slow down the neutrons to thermal energies

The binding energy per nucleon of deuterium and helium atom is 1.1 MeV and 7.0 MeV. If two deuterium nuclei fuse to form a helium atom, the energy released is:

1. 19.2 MeV

2. 23.6 MeV

3. 26.9 MeV 

4. 13.9 MeV

In a fission reaction,

$$\(^{236}_{92}U\rightarrow ~^{117}X~+~^{117}Y~+~^1_0n~+~^1_0n,\) the binding energy per nucleon of X and Y is 8.5 MeV whereas that of \(^{236}U\) is 7.6 MeV. The total energy liberated will be about:

1. 2000 MeV

2. 200 MeV

3. 2 MeV 

4. 1 keV

A nuclear decay is expressed as 

${}_{6}C_{11}\to {}_{5}B_{11}+{\beta }^{+}+X$

Then the unknown particle X is:

1. Neutron 

2. antineutrino

3. proton 

4. neutrino

When a deuterium is bombarded on ${}_{8}O_{16}$ nucleus, an $\alpha$-particle is emitted, then the product nucleus is:

1. ${}_{7}N_{13}$ 

2. ${}_{5}B_{10}$

3. ${}_{4}B{e}_9$ 

4. ${}_{7}N_{14}$

A nuclear reaction given by \({ }_{Z}^{A} \mathrm{~X} \rightarrow{ }_{Z+1}^{A} \mathrm{Y}+e^{-}+\bar{v}\) represents:
1. fusion
2. fission
3. \(\beta^{-} \)-decay
4. \(\gamma \)-decay

The mass of ${}_{7}N_{15}$ is 15.00011 amu, mass of ${}_{8}O_{16}$ is 15.99492 amu and $m_p$= 1.00783 amu. Determine the binding energy of the last proton of \({ }_8 O_{16}\).

1. 2.13 MeV

2. 0.13 MeV 

3. 10 MeV 

4. 12.13 MeV

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

1. increasing the temperature.

2. increasing the pressure.

3. chemical reaction.

4. it is not possible.