Assertion: A body becomes weightless at the centre of earth.
Reason: As the distance form centre of earth decreases, acceleration due to gravity increases.

Options

A. If both the assertion and reason are true and reason is a true explantion of the assertion.
B. If both the assertion and reason are true but the reason is not true the correct explantion of the assertion.
C. If the assertion is true but reason false
D. If both the assertion and reason are false.

Explanation

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

### Step 1: Understanding the Assertion
The assertion states that "A body becomes weightless at the center of the Earth."
- At the center of the Earth, the gravitational forces from all directions cancel out. This means that the net gravitational force acting on a body at the center is zero. Therefore, the body experiences no weight, which corresponds to the feeling of weightlessness.

### Step 2: Understanding the Reason
The reason states that "As the distance from the center of the Earth decreases, acceleration due to gravity increases."
- This statement is incorrect. As we move towards the center of the Earth, the acceleration due to gravity actually decreases. The formula for gravitational acceleration inside the Earth is given by:
\[ g' = g \left(1 - \frac{d}{R}\right) \]
where \(g'\) is the acceleration due to gravity at a distance \(d\) from the center, \(g\) is the acceleration due to gravity at the surface, and \(R\) is the radius of the Earth. As \(d\) approaches \(R\) (the radius), \(g'\) approaches zero.

### Step 3: Conclusion
- Since the assertion is true (a body does become weightless at the center of the Earth) and the reason is false (the acceleration due to gravity does not increase as we move towards the center), the correct answer is that the assertion is true but the reason is false.

### Final Answer
- The correct option is C: Assertion is true but reason is false.

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