Which scientist is associated with the term 'Nuclein'?

Three positive charges of equal value $q$ are placed at the vertices of an equilateral triangle. The resulting lines of force should be sketched as in

The branch of botany that deals with the study of algae is known as:

The $24$ hour (diurnal) rhythm of our body,such as the sleep-wake cycle,is regulated by the hormone:

The figure shows a transparent sphere of radius $R$ and refractive index $\mu$. An object $O$ is placed at a distance $x$ from the pole of the first surface so that a real image is formed at the pole of the exactly opposite surface. If $x = \infty$,then the value of $\mu$ is

According to molecular orbital theory,the total number of bonding electron pairs in $O_2$ is