Question 1
The answer is (B).
The magnetic flux linked with the coil is given by:
$\Phi = BA$
where $B$ is the magnetic field and $A$ is the area of the coil.
In this case, the plane of the coil is perpendicular to the direction of the field, so the magnetic flux is:
$\Phi = BA = BR^2$
Question 2
The answer is (C).
The magnitude of the induced emf in the loop is given by:
$\epsilon = \frac{d\Phi}{dt}$
where $\Phi$ is the magnetic flux and $t$ is time.
In this case, the magnetic flux changes from $BA$ to $-BA$ when the loop is turned through 180° about a diagonal. So the magnitude of the induced emf is:
$\epsilon = \frac{d\Phi}{dt} = \frac{2BA}{t} = 2BRa^2$
