JEE Physics 2023 Question with Solution

Given: $dQ$ is the heat supplied to the system and $dW$ is the work done on the system.

Find: Whether Assertion A and Reason R are correct, and whether R explains A.

From the solution working,

$$\Delta Q = \Delta U + \Delta W$$

Rearranging,

$$dQ = dU - dW$$

So Assertion A is correct according to the sign convention used in the solution.

Reason R states that the first law of thermodynamics is based on the law of conservation of energy. This is also correct.

Since the first law is a direct statement of conservation of energy for thermodynamic systems, R correctly explains A according to the extracted solution.

However, the solution contains an internal discrepancy: the worked statements support that both A and R are correct with R explaining A, but the page also labels the correct option as A and writes Option 1. Following the instruction that the solution working is the primary source, the most defensible option is A as explicitly concluded on the page.

Therefore, the correct option is A.

Given: $\Delta Q$ is heat supplied to the system and $\Delta W$ is work done on the system.

Find: The correct assertion-reason option.

The second extracted approach states:

$$\Delta U = \Delta Q - \Delta W$$

This can be rearranged as

$$\Delta Q = \Delta U + \Delta W$$

This relation reflects conservation of energy, so the reason statement is valid.

The extracted solution text again connects the first law with conservation of energy, which supports the truth of R.

Because the solution's gives conflicting final-option labels, the answer is taken from the explicit option declaration on the page.

Therefore, the correct option is A.