QJEEAdv15Phfcd6: JEE Advanced 2015 Physics - Class 12 JEEAdv15Phfcd6 Solution: Match the nuclear processes given in Column I with the…

The nuclear fusion is responsible for energy production in stars via fusion of hydrogen nuclei into helium nuclei. In sun, the fusion takes place dominantly by proton-proton cycle, $4_1^1H \to _2^4He + 2{e^ + } + 2\nu + 2\gamma$ . The neutrino ( $\nu$ ) and $\gamma$ -rays emissions are parts of this fusion reaction.

The uranium based fission reactions involve absorption of thermal neutrons by ${}_{92}^{235}$ U nuclei to produce the highly fissionable ${}_{92}^{236}$ U nuclei. This nuclei then fissions into two parts e.g., ${}_{92}^{236}$ U $\to$ ${}_{63}^{137}$ I + ${}_{39}^{97}$ Y + 2n. The fission fragments are unstable and undergo $\beta$ -decay to reduce their neutron to proton ratio. The fragments are generally formed in excited states and consequently emit $\gamma$ -rays. The heavy water (D₂O) is used as a moderator to slow down the fast moving neutrons.

In $\beta$ -decay, a neutron is converted into a proton. In this process, an electron and an antineutrino are created and emitted from the nucleus, n $\to$ p + e ^$-$ + $\overline v$ . The $\beta$ -decay in ${}_{27}^{60}$ Co $\to$ ${}_{28}^{60}$ Ni + e ^$-$ + $\overline v$ . The daughter nuclei ${}_{28}^{60}$ Ni is formed in excited state and comes to ground state by $\gamma$ -ray emission.

The $\gamma$ -rays are high energy electromagnetic rays. These rays are generally emitted when a nuclei in excited state (high energy) makes a transition to a lower state (low energy).