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

How many cyclic structures are possible for $C_4H_6$?

How many stereoisomers are possible for the following molecule?

In a $500 \ mL$ flask,the degree of dissociation of $PCl_5$ at equilibrium is $40 \%$ and the initial amount is $5 \ moles$. The value of equilibrium constant in $mol \ L^{-1}$ for the decomposition of $PCl_5$ is

If $A$ is the areal velocity of a planet of mass $M$,its angular momentum is

Select the correct pair from the following.