Which of the following is used as moderator(s) in a nuclear reactor ?

1. Cadmium rods
2. Graphite
3. Heavy Water
4. Both (2) and (3)

The source of energy of the sun and stars is obtained from the nuclear fusion of :

1. uranium
2. thorium
3. hydrogen
4. ²³⁵₉₂U

Complete the following nuclear fission reactions:

(a) ${}_{92}^{235}\text{U}${92}^{235}\text{U} + ${0}^{1}\text{n}$ ⟶ ${}_{56}\text{Ba}${56}\text{Ba} + $^{92}\text{Kr}$ + 3 ${0}^{1}\text{n}$ + …….

(b) ${}_{92}^{235}\text{U}${92}^{235}\text{U} + ${0}^{1}\text{n}$ ⟶ $^{148}\text{La}$ + ${}_{35}^{85}\text{Br}${35}^{85}\text{Br}+ …… ${0}^{1}\text{n}$ + energy

Complete the following fusion reactions —

(a) ${}_2^3\text{He}${2}^{3}\text{He} + ${1}^{2}\text{H}$ ⟶ ${}_2\text{He}${2}\text{He} + ${1} \text{H}$ + energy

(b) ${}_1^2\text{H}${1}^{2}\text{H} + ${1}^{2}\text{H}$ ⟶ $_{2}\text{He}$ + $^{1} \text{n}$ + energy