The unit of magnetic flux is

$A$ circular loop of radius $R$ carrying current $I$ lies in the $x-y$ plane with its centre at the origin. The total magnetic flux through the $x-y$ plane is:

Which of the following statements regarding magnetic lines of force is correct?

Given below are two statements $:$ one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A) :$ Magnetic monopoles do not exist.
Reason $(R) :$ Magnetic field lines are continuous and form closed loops.
In the light of the above statements, choose the most appropriate answer from the options given below.

The diagram shows the magnetic field lines of a bar magnet. $A$ coil is moved from above the magnet to below it and then back to the original position. Which of the following graphs best represents the variation of magnetic flux $\Phi$ through the coil with time $t$?

The dimensions of magnetic flux are