In male cockroaches,sperms are stored in which part of the reproductive system?

Which of the following units represents the largest amount of energy?

Particles of masses $m, 2m, 3m, \dots, nm$ grams are placed on the same line at distances $l, 2l, 3l, \dots, nl$ cm from a fixed point. The distance of the centre of mass of the particles from the fixed point (in cm) is

The radius of a circular plate is increasing at the rate of $0.01 \text{ cm/s}$ when the radius is $12 \text{ cm}$. Then, the rate at which the area increases, is

The reduction potential of a hydrogen half-cell will be negative if:

If the tangents at the extremities of a chord $PQ$ of a parabola intersect at $T$,then the distances of the focus of the parabola from the points $P, T, Q$ are in-