Which one of the following is an example of cleistogamy?

The ratio of the radii of nuclei $_{13}Al^{27}$ and $_{52}X^A$ is $3:5$. The number of neutrons in the nucleus of $X$ will be:

Which of the following pairs is incorrect?

$A$ transformer works on the principle of

The yellow colour solution of $Na_2CrO_4$ changes to orange-red on passing $CO_2$ gas due to the formation of

A small block of mass $m$ slides down from the top of a frictionless inclined surface, while the inclined plane is moving towards left with constant acceleration $a_{0}$. The angle between the inclined plane and ground is $ heta$ and its base length is $L$. Assuming that initially the small block is at the top of the inclined plane, the time it takes to reach the lowest point of the inclined plane is . . . . . . . .