Modulus it rigidity of ideal liquids is

Options

A. infinity
B. zero
C. unity
D. some finite small non-zero constant value.

Explanation

To solve the question regarding the modulus of rigidity of ideal liquids, we can follow these steps:

### Step 1: Understand the Concept of Modulus of Rigidity
The modulus of rigidity (also known as shear modulus) is defined as the ratio of shear stress to shear strain in a material. It quantifies how a material deforms under shear stress.

### Step 2: Define Ideal Liquids
An ideal liquid is a theoretical concept in fluid mechanics. It is characterized by the absence of viscosity, meaning it has no internal friction. In other words, an ideal liquid flows without any resistance.

### Step 3: Analyze Shear Stress and Shear Strain
For a material to have a modulus of rigidity, it must be able to develop shear stress when subjected to a shear strain. In the case of an ideal liquid:
- Shear stress is defined as the force per unit area applied parallel to the surface.
- Shear strain is the deformation (change in shape) that occurs in response to the applied shear stress.

### Step 4: Determine Shear Stress in Ideal Liquids
Since ideal liquids have no viscosity, they do not develop any shear stress when subjected to shear strain. Therefore, the shear stress in an ideal liquid is zero.

### Step 5: Calculate the Modulus of Rigidity
Using the formula for modulus of rigidity:
\[ \text{Modulus of Rigidity} (G) = \frac{\text{Shear Stress}}{\text{Shear Strain}} \]
Since the shear stress is zero for an ideal liquid, we can substitute this into the equation:
\[ G = \frac{0}{\text{Shear Strain}} = 0 \]

### Conclusion
Thus, the modulus of rigidity of an ideal liquid is zero.

### Final Answer
The modulus of rigidity of ideal liquids is **zero**.

---