To study the age of excavated materials of archeological significance, we study the rate of decay of an isotope of :

1. uranium
2. cobalt
3. carbon
4. chlorine

A radioactive nucleus emits a beta particle. The position of daughter nucleus in the periodic table as compared to the parent nucleus after emitting a beta particle is :

1. at the same place
2. one place higher
3. one place lower
4. two places lower

The correct representation of γ emission is :

1. $_{Z}^{A}\text{P} \longrightarrow \space _{Z-1}^{ \space \space \space \space \space A}\text{Q} + γ$
2. $_{Z}^{A}\text{P} \longrightarrow \space _{Z-2}^{A-4}\text{Q} + \space _{2}^{4}γ$
3. $_{Z}^{A}\text{P} \longrightarrow \space _{Z}^{A}\text{P} + γ$
4. $_{Z}^{A}\text{P} \longrightarrow \space _{Z-1}^{A}\text{P} + γ$

Assertion (A): Out of α, β and γ radiation, α-particles have maximum penetrating power.

Reason (R): The α-particles are the heaviest amongst the three.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true and R is not the correct explanation of A.
3. assertion is false but reason is true.
4. assertion is true but reason is false.