Question

a. In the given figure a radioactive source is placed inside a lead block. Identify the rays incident on the photographic plates.

b. Which of the following statement is correct. 

1. Gamma rays consist of high energy neutrons. 

2. Alpha rays are equivalent to singly ionized He atoms.

3. Protons and neutrons have exactly the same mass.

4. Beta rays are same as cathode rays.

c. How many alpha and beta particles are emitted in the following reaction.

₉₂U²³⁸ → ₈₂Pb²⁰⁶

Answer 1

a. 

• 1 – Alpha
• 2-Gamma 
• 3 – Beta

b. 4. Beta rays are same as cathode rays 

c.  ₉₂U²³⁸ → ₈₂Pb²⁰⁶

Difference in mass number = 32

Mass number of one alpha particle = 4

Hence number of alpha particles = 8

Change in atomic number = 10

Change in atomic number due to alpha particles = 16

Charge of beta particles = -1

Hence number of beta particles emitted = 6