Question

An atomic nucleus A is composed of 84 protons and 128 neutrons.

1. The nucleus A emits an alpha particle and is transformed into nucleus B. What is the composition of nucleus B?
2. The nucleus B emits a beta particle is transformed into nucleus C. What is the composition of nucleus C?
3. Does the composition of nucleus C change if it emits gamma radiations?

Answer 1

Given: Number of protons in nucleus A = 84

Number of neutrons in nucleus A = 128

(i) When nucleus A emits an alpha particle, the number of protons decreases by 2 and the number of neutrons decreases by 2.

Number of protons = 84 − 2

= 82

Number of neutrons = 128 − 2

= 126

Therefore, nucleus B contains 82 protons and 126 neutrons.

(ii) When nucleus B emits a beta (\(\beta^-\)) particle, one neutron changes into a proton.

Number of protons = 82 + 1

= 83

Number of neutrons = 126 − 1

= 125

Therefore, nucleus C contains 83 protons and 125 neutrons.

(iii) No, the composition of nucleus C remains unchanged because gamma radiation carries neither mass nor charge. Hence, the number of protons and neutrons remains the same.