JEE Physics 2025 Question with Solution

Given: Four reactions in LIST-I are to be matched with the descriptions in LIST-II.

Find: The correct matching and hence the correct option.

Classify each reaction using the reactants and products shown in the equation.

1. Reaction A

A heavy nucleus splits into lighter nuclei and neutrons, so this is fission. Therefore, A \rightarrow III.

2. Reaction B

This is a usual chemical reaction involving molecules, so B \rightarrow I.

3. Reaction C

Two light nuclei combine to form a heavier nucleus, so this is fusion. The solution identifies it as fusion with positive Q value, hence C \rightarrow II.

4. Reaction D

This is also a fusion reaction. The solution identifies it as fusion with negative Q value, hence D \rightarrow IV.

So the correct matching is:

Therefore, the correct option is B.

Given: A matching question on fission, fusion, and chemical reaction.

Find: Which option correctly matches all entries.

• A: $^{236}_{92} U \rightarrow ^{94}_{38} Sr + ^{140}_{54} Xe + 2n$

• A very heavy nucleus breaks into two medium nuclei with neutrons emitted.

• This is the characteristic signature of nuclear fission.

• Hence, A - III.

• B: $2H_2 + O_2 \rightarrow 2H_2O$

• Hydrogen and oxygen molecules combine to form water.

• No nuclear species are changing; this is a chemical reaction.

• Hence, B - I.

• C: $^3_1 H + ^2_1 H \rightarrow ^4_2 He + n$

• Two light nuclei combine.

• This is fusion, and the provided solution states that energy is released, so it has positive Q value.

• Hence, C - II.

• D: $^1_1 H + ^3_1 H \rightarrow ^4_2 H + \gamma$

• This is again a combination of light nuclei, so it is fusion.

• The provided solution classifies it as fusion with negative Q value.

• Hence, D - IV.

Thus, the final match is A-III, B-I, C-II, D-IV.

Therefore, the correct option is B.