During transcription,the site on $DNA$ where $RNA$ polymerase binds is called .........

Viruses have

$A$ straight wire of length $20 \ cm$ carrying a current of $\frac{3}{\pi^2} \ A$ is bent in the form of a circle. The magnetic field at the centre of the circle is

The standard deviation of the numbers $22, 26, 28, 20, 24, 30$ is

$A$ bullet of mass $0.02 \ kg$ travelling horizontally with velocity $250 \ ms^{-1}$ strikes a block of wood of mass $0.23 \ kg$ which rests on a rough horizontal surface. After the impact,the block and bullet move together and come to rest after travelling a distance of $40 \ m$. Find the coefficient of sliding friction of the rough surface. (Take $g = 9.8 \ ms^{-2}$)

Which one of the following conditions is incorrect for a well-behaved wave function $(\psi)$?