Question

In the following reaction

_ZX^A →_Z+1 Y^A →_Z-1 K^A-4 →_z-1 K^A-4

radioactive radiations are emitted in the sequence:

1. α, β, γ
2. β, α, γ
3. γ, α, β
4. β, γ, α

Answer 1

Correct Answer - Option 2 : β, α, γ

Concept:

Alpha	Alpha particles charge is 2e - and mass is 4 times that of hydrogen. When an alpha particle is ejected from the nucleus the element loses 2 units in atomic number and 4 units in mass number.
Beta	Beta particles have a charge equal to that of an electron. Ejection of a beta particle changes the atomic number by plus one but no change in mass number occurs.
Gamma	Gamma Rays do not have any charge of or mass.

Explanation:

• The equation given is

ZXA →Z+1 YA →Z-1 KA-4 →z-1 KA-4

• In the first equation,

 ZXA →Z+1 YA,

• The mass number is unchanged whereas the atomic number is increased by one unit, hence beta particle is emitted.
• In the second equation

Z+1 YA →Z-1 KA-4,

• The mass number decreases by 4 units and the mass number decreases by two units. Hence, the α particle is emitted.
• In the last equation,

Z-1 KA-4 →z-1 KA-4 

• There is no change in charge or mass thus the particle emitted is γ.

Hence, the order in which the particles are emitted is β, α, γ.

Positron	Positrons are ejected when a proton is converted into a neutron. The ejection of positron lowers the atomic number by one unit but leaves the mass number unchanged.
Anti-neutrino	Antineutrinos are ejected when a neutron is converted into a proton. A beta particle is also created in this process. It is represented by β +.