1. Calculate the energy produced when \(1\ kg\) of substance is fully converted into energy. [Note: \(C\ =\) \(3 \times{10^8}\) \(ms^{-1}\)] [March 2015 and March 2014]
 
According to Einstein's mass-energy equivalence,
 
E=i×ii
 
On substituting the given values in the above formula, we get
 
E=i×i×ii
 
=i×ii \(J\)

2. What is moderator? [June 2011]
 
A moderator is utilised to slow down the high-energy,  neutrons to produce neutrons. The most commonly used moderator is , out of which  is the efficient moderator.

3. Water is preferred as a coolant. Why? [June 2011]
 
A coolant is mainly used to produce  by removing the  produced in the reactor core. This steam helps to run a  to generate . Hence, water is the most efficient and commonly used coolant.

4. Name any four research reactors located in \(BARC\). [June 2011]
 
(i)
 
(ii)
  
(iii)
  
(iv)

5. Give any five differences between Natural radioactivity and Artificial radioactivity. [June 2011]
 
Natural radioactivity
Artificial radioactivity
Emission of radiation due to the  of a nucleus.
Emission of radiation due to the disintegration of a nucleus through the  process.
 radiation is emitted. Elementary particle like is emitted.
It is a  process. It is an  process.
Requires  energy to carry out the process. Requires  energy to carry out the process.
 is an example.  is an example.