1. The atomic number of natural radioactive element is __________. [April 2013]

2. When a radioactive nucleus disintegrates by emitting beta particle, its atomic number __________. [March 2010]
 
3. Match the following: [September 2015]
 
Column A
Column B
(a) Henri Becqurel
(b) Otto Hahn

4. Gamma rays are harmful radiations emitted by natural radioactive substances.
(a) Which are the other radiations emitted by natural radioactive substances?
(b) What is the unit of nuclear radiation? [September 2015] and [March 2014]
 
(a) The other radiations emitted by natural radioactive substances are .
 
(b) The unit of nuclear radiation is .

5. In the nuclear reaction given below, a nucleus \(X\) changes into another nucleus \(Y\).
 
\(_{88}X^{226}\) \(\rightarrow\) \(Y\) \(+\) \(_{2}He^{4}\)
 
What is the atomic number and mass number of \(Y\)? [March 2014]
 
Atomic number of \(Y\) is .
 
Mass number of \(Y\) is .