The circuit shown here is used to compare the emf of two cells $E_1$ and $E_2$ $(E_1 > E_2)$. The null point is at $C$ when the galvanometer is connected to $E_1$. When the galvanometer is connected to $E_2$,the null point will be

For an ellipse with eccentricity $e = \frac{1}{2}$,the centre is at the origin. If one directrix is $x = 4$,then the equation of the ellipse is

Convergent evolution is illustrated by

$A$ radioactive material of half-life $T$ was produced in a nuclear reactor at different instants. The quantity produced the second time was twice that produced the first time. If their present activities are $A_1$ and $A_2$ respectively,then their age difference equals:

In which of the following pairs,the central atoms have the same number of lone pairs of electrons?

$A$ solid sphere and a disc of same mass $M$ and radius $R$ are kept such that their curved surfaces are in contact and their centers lie along the same horizontal line. The moment of inertia of the two-body system about an axis passing through their point of contact and perpendicular to the plane of the disc is