The unit of potential energy is

$A$ physical quantity is measured and its value is found to be $nu$, where $n$ is the numerical value and $u$ is the unit. Then which of the following relations is true?

The unit of angular acceleration in the $SI$ system is

Fill in the blanks:
$(a)$ $1 \, rad = \dots \text{ degrees}$
$(b)$ Light year is a unit of $\dots$
$(c)$ The solid angle subtended by a hemisphere at its center is $\dots$

The unit of power is:

$J s$ is the unit of . . . . . . physical quantity.