What is meant by compressible fluids?

A given shaped glass tube having uniform cross-section is filled with water and is mounted on a rotatable shaft as shown in figure. If the tube is rotated with a constant angular velocity $\omega$ then

What is meant by irrotational flow?

Water stands at a depth of $15 \mathrm{m}$ behind a reservoir dam. A horizontal pipe $4 \mathrm{cm}$ in diameter passes through the dam $6 \mathrm{m}$ below the surface $01$ water as shown. There is a plug which secures the pipe opening. Then find the friction between the plug and pipe wall.

This question consists of two statements each printed as assertion and reason. While answering this question you are required to choose any one of the five responses.

Assertion: Bulk modulus of an incompressible liquid is infinite.

Reason: Compressibility is inverse of bulk modulus.

Represent the union of two sets by Venn diagram for each of the following.

$X=\{x | x$ is a prime number between $80$ and $100\}$

$Y=\{y | y$ is an odd number between $90$ and $100\}$

This question consists of two statements each printed as assertion and reason. While answering this question you are required to choose any one of the five responses.

Assertion: Density of an incompressible liquid is constant.

Reason: An ideal fluid is incompressible.