What will be the phase difference between virtual voltage and virtual current,when the current in the circuit is wattless (in $^o$)?

$A$ line segment $l$ of length $a \ cm$ is rotated about a vertical line $L$ keeping the line $l$ in one of the following three positions: $(I)$ $l$ is parallel to $L$ and is at a distance of $r \ cm$ from $L$,$(II)$ $l$ is perpendicular to $L$ and its mid-point is at a distance $r \ cm$ from $L$,$(III)$ $l$ and $L$ are in the same plane and $l$ is inclined to $L$ at an angle $30^{\circ}$ with its mid-point at a distance $r \ cm$ from $L$. Let $A_1, A_2, A_3$ be the areas so generated. If $r > (a / 2)$,then

If $A, B$,and $C$ are three sets,then $A - (B \cup C)$ is equal to

If we use pyrene $(CCl_4)$ in the Riemer-Tiemann reaction in place of chloroform,the product formed is

The suspension of slaked lime in water is known as

The height at which the weight of a body becomes $1/16^{th}$ of its weight on the surface of the earth (radius $R$) is: (in $R$)