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

A nuclear decay is expressed as:
\(_{6}^{11}\mathrm{C}\rightarrow _{5}^{11}\mathrm{B}+\beta^{+}+\mathrm{X}\)
Then the unknown particle \(X\) is:
1. neutron 
2. antineutrino
3. proton 
4. neutrino

A nuclear reaction given by \({ }_{Z}^{A} \mathrm{~X} \rightarrow{ }_{Z+1}^{A} \mathrm{Y}+e^{-}+\bar{v}\) represents:

The mass of \({}_{7}^{15}\mathrm{N}\) is \(15.00011\) amu, mass of \({}_{8}^{16}\mathrm{O}\) is \(15.99492\) amu and \(m_p = 1.00783\) amu. Determine the binding energy of the last proton of \({ }_{8}^{16}\mathrm{O}\).
1. \(2.13\) MeV
2. \(0.13\) MeV 
3. \(10\) MeV 
4. \(12.13\) MeV

The minimum wavelength of X-rays produced by electrons accelerated by a potential difference of V volt is equal to 

1. $\frac{eV}{hc}$ 

2. $\frac{eh}{cV}$ 

3. $\frac{hc}{eV}$ 

4. $\frac{cV}{eh}$

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.

The energy released by the fission of one  uranium atom is 200 MeV. The number of fission per second required to produce 3.2 W of power is (Take, 1 eV = 1.6$\times$${10}^{-19} J$) [WB JEE 2010]

1. ${10}^7$ 

2. ${10}^{10}$ 

3. ${10}^{15}$

4. ${10}^{11}$