Which of the following halogens undergoes disproportionation in water?

$A$ uniform rod of mass $M$ and length $L$ is placed on a smooth horizontal surface. $A$ horizontal force $F$ is applied at one end of the rod perpendicular to its length. The acceleration of the centre of mass of the rod is:

Suppose there is a hole in a copper plate. On heating the plate,the diameter of the hole would:

In the given circuit,if point $C$ is connected to the earth and a potential of $+2000 \, V$ is applied to point $A$,what is the potential of point $B$ in volts?

The condition that the roots of $x^3-b x^2+c x-d=0$ are in geometric progression is

The half-life of a radioactive nucleus is $50 \ days$. The time interval $(t_2 - t_1)$ between the time $t_2$ when $\frac{2}{3}$ of it has decayed and the time $t_1$ when $\frac{1}{3}$ of it has decayed is ......... $days$.