Ethanol when reacted with $PCl_5$ gives $A$,$POCl_3$ and $HCl$. $A$ reacts with silver nitrite to form $B$ (major product) and $AgCl$. $A$ and $B$ respectively are

Which of the following taxonomical aids is being described by the given statements $(i-iv)$?
$(i)$. They are generally established in educational institutes.
$(ii)$. They have collections of preserved plant and animal specimens for study and reference.
$(iii)$. Insects are preserved in boxes after collecting,killing and pinning.
$(iv)$. They often have collections of skeletons of animals too.

The resolving limit of a healthy human eye is about

Which property of hydrogen distinguishes it from alkali metals?

The bonds present in ${N_2}{O_5}$ are ........