Explanation:

- A partner introduced additional capital of Rs30,000, which generally earns no interest unless specified by the partnership agreement.

- The partner also advanced a loan of Rs40,000 to the firm at the beginning of the year.

- Typically, interest on loans from partners is paid at a certain agreed rate, commonly around 6% annually unless otherwise stated.

Let's break down each option:

- Option 1: Rs4,200 - Assumes an interest rate of 10.5% (4,200/40,000). This is unusually high for partner loans.

- Option 2: Rs2,400 - A 6% interest rate on Rs40,000, which aligns with common practice.

- Option 3: Nil - Implies no interest, which is unlikely for loans.

- Option 4: Rs1,800 - Suggests a 4.5% interest rate, which is lower than typical rates.

Option 2: Rs2,400 appears correct as it reflects a common 6% interest rate on the loan.

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