What is an ideal liquid ?

Explanation

### Step-by-Step Solution:

1. **Definition of Ideal Liquid**: An ideal liquid is a theoretical concept in fluid mechanics. It is a type of fluid that is used to simplify the analysis of fluid motion.

2. **Zero Viscosity**: One of the key characteristics of an ideal liquid is that it has zero viscosity. This means that it can flow without any resistance or energy loss due to internal friction. In practical terms, this implies that there is no energy lost when the liquid moves.

3. **Incompressibility**: An ideal liquid is also considered incompressible. This means that the density of the liquid remains constant regardless of the pressure applied to it. In other words, the volume of the liquid does not change when pressure is applied.

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