How many bridging oxygen atoms are present in $P_4O_{10}$?

The technique used to make numerous copies of a specific segment of $DNA$ quickly and accurately is

Identify the logic operation carried out by the following circuit.

If the angle $2 \theta$ is acute,then the acute angle between the pair of straight lines $x^2(\cos \theta - \sin \theta) + 2xy \cos \theta + y^2(\cos \theta + \sin \theta) = 0$ is:

All but one of the following compounds react with aniline to give acetanilide. Which one does not?

Nitrobenzene on reduction using zinc in alkaline medium results in $X$. The number of $\sigma$ and $\pi$ bonds in $X$ is