Different conformations of the same molecule are called

Which of the following diseases is caused by a protozoan?

The number of ways that $8$ beads of different colours can be strung as a necklace is

$\sqrt{10 - \sqrt{24} - \sqrt{40} + \sqrt{60}} = ?$

In an $ac$ circuit $I = 100 \sin(200 \pi t)$. The time required for the current to achieve its peak value will be

$A$ lead shot of $1\, mm$ diameter falls through a long column of glycerine. The variation of its velocity $v$ with distance covered is represented by