Analyze Statement-1

Statement-1 says:

Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion.

This is true.

Reason:

The binding energy per nucleon curve shows that nuclei become more stable as binding energy per nucleon increases, up to about iron ($A \approx 56$).

• Heavy nuclei (like uranium) have lower binding energy per nucleon than medium-mass nuclei, so when they split (fission), the products have higher binding energy per nucleon.
• Light nuclei (like hydrogen isotopes) also have lower binding energy per nucleon than medium nuclei, so when they combine (fusion), the product has higher binding energy per nucleon.

In both cases, the increase in total binding energy means energy is released.

Therefore, Statement-1 is true.

Analyze Statement-2

Statement-2 says:

For heavy nuclei, binding energy per nucleon increases with increasing $Z$ while for light nuclei it decreases with increasing $Z$.

This is false.

Correct trend:

The binding energy per nucleon versus mass number (or roughly with increasing nuclear size) behaves as follows:

• For light nuclei, binding energy per nucleon increases as nuclei become heavier.
• It reaches a maximum near iron.
• For heavy nuclei, binding energy per nucleon decreases as nuclei become heavier.

So Statement-2 has the trend exactly reversed.

Choose the correct option

• Statement-1: True
• Statement-2: False

Hence the correct option is:

$\boxed{\text{D}}$

Compare with stored correct answer

Stored correct answer = D

My derived answer = D

So, the derived answer agrees with the stored correct answer.