Assertion : If by mistake, a voltmeter is connected in series, then circuit will burn.
Reason : Current will drastically decrease in the circuit.

Options

A. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B. If both Assertion and Reason are true and Reason is not correct explanation of Assertion.
C. If Assertion is true but Reason is false.
D. If Assertion is false but Reason is true.

Answer

To solve the assertion and reason question, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states: "If by mistake, a voltmeter is connected in series, then the circuit will burn."

- **Analysis**: A voltmeter is designed to measure the potential difference across two points in a circuit and is meant to be connected in parallel. If a voltmeter is mistakenly connected in series, it will introduce a high resistance into the circuit.

### Step 2: Understand the Reason
The reason states: "Current will drastically decrease in the circuit."

- **Analysis**: When a voltmeter is connected in series, the total resistance of the circuit increases significantly because voltmeters have high internal resistance. According to Ohm's Law (V = IR), if the resistance increases, the current (I) must decrease for a given voltage (V). Thus, the current will indeed decrease drastically.

### Step 3: Conclusion on Assertion and Reason
- The assertion claims that the circuit will burn, which is incorrect. The increased resistance from the voltmeter will lead to a decrease in current, which means that there will be less heating in the circuit, not more. Therefore, the circuit will not burn.
- The reason is correct; connecting a voltmeter in series will lead to a drastic decrease in current.

### Final Answer
- The assertion is **false**.
- The reason is **true**.

Thus, the correct conclusion is that the assertion is false while the reason is true.

---