Question

Staements I: `._zX^4` undergoes `2 alpha`-decays, `2 beta`-decays (negative `beta`) and `2 gamma`-decays. As a result, the daughter product is `._z._-2X^(A-B)`.
Staements II: In `alpha`-decay, the mass number decreases by 4 unit and atomic number decreases by `2` unit. In `beta`-decay (negative `beta`), the mass number remains unchanged and atomic number increases by `1` unit. In `gamma`-decay, mass number and atomic number remain unchanged.
A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false
D. If assertion is false but reason is true.

Answer 1

Correct Answer - A
(a) In `alpha-`particle, the mass number decreases by `4` and atomic number decreases by `2`. In `beta-`decay, the mass number does not change but atomic number increases by `1`. In `gamma`-decay, the atomic and mass number remain unchanged.
The reaction can be summarised as
`._Z X^A overset (2 alpha)rarr ._(Z-4) Y^(A - 8) overset (2 beta)rarr ._(Z -2) Y^(A-8) overset (2 gamma)rarr ._(Z-2) Y^(A-8)`.