A body measures 5 N in air and 2 N when put in water. The buoyant force is

Options

A. 7 N
B. 9 N
C. 3 N
D. None of these

Explanation

To find the buoyant force acting on the body when it is submerged in water, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Weight of the Body in Air:**
The weight of the body in air is given as 5 N. This weight can be represented as:
\[ W = Mg = 5 \, \text{N} \]
where \( M \) is the mass of the body and \( g \) is the acceleration due to gravity.

2. **Identify the Apparent Weight of the Body in Water:**
When the body is submerged in water, its apparent weight is given as 2 N. This apparent weight can be expressed as:
\[ W' = Mg - F_b = 2 \, \text{N} \]
where \( F_b \) is the buoyant force acting on the body.

3. **Set Up the Equation:**
From the above two equations, we can set up the following equation:
\[ 5 \, \text{N} - F_b = 2 \, \text{N} \]

4. **Solve for the Buoyant Force:**
Rearranging the equation to solve for \( F_b \):
\[ F_b = 5 \, \text{N} - 2 \, \text{N} \]
\[ F_b = 3 \, \text{N} \]

5. **Conclusion:**
The buoyant force acting on the body when it is submerged in water is:
\[ F_b = 3 \, \text{N} \]

### Final Answer:
The buoyant force is **3 N**.