In case of a liquid

Options

A. only bulk modulus is defined
B. only bulk modulus and Young's modulus are defined
C. only bulk modulus and shear modulus are defined
D. all the three moduli (bulk, Young's and shear) are defined

Answer

To solve the question regarding the properties of liquids and their modulus, we can follow these steps:

### Step 1: Understand the Moduli
- **Young's Modulus**: This is a measure of the stiffness of a solid material and is defined as the ratio of tensile stress to tensile strain. It is applicable to solids.
- **Shear Modulus**: This measures the material's response to shear stress and is also applicable to solids.
- **Bulk Modulus**: This measures a substance's response to uniform pressure applied in all directions and is defined as the ratio of volumetric stress to the change in volume (volumetric strain). It is applicable to both liquids and solids.

### Step 2: Identify the Properties of Liquids
- Liquids do not have a definite shape and can flow, which means they cannot sustain shear stress like solids do. Therefore, Young's modulus and shear modulus are not applicable to liquids.
- Liquids can be compressed, and their volume can change under pressure, which is why bulk modulus is relevant.

### Step 3: Analyze the Options
- The question provides four options regarding which moduli are defined for liquids:
1. Only bulk modulus is defined.
2. Only bulk modulus and Young's modulus are defined.
3. Only bulk modulus and shear modulus are defined.
4. All three moduli (bulk, Young's, and shear) are defined.

### Step 4: Determine the Correct Answer
- Since Young's modulus and shear modulus are not applicable to liquids, the only modulus that is defined for liquids is the bulk modulus. Therefore, the correct option is:
- **Option A: Only bulk modulus is defined.**

### Final Answer
The correct answer is **Option A: Only bulk modulus is defined.**

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