How many secondary carbon and hydrogen atoms are present in the molecule $CH_3-CH(Br)-CH(Br)-CH_3$ respectively?

Cyclohexa-$1,3$-diene contains . . . . . . vinylic and . . . . . . allylic hydrogen atoms?

Fill in the blanks:
$(1)$ Two isomers of butane are $n$-butane and isobutane. The relation of the number of $\sigma$ and $\pi$-bonds in them is .......... .
$(2)$ .......... is present in the structure of a heterocyclic compound.
$(3)$ Cyclohexene is a .......... type and furan is a .......... type of compound.
$(4)$ .......... type of $3-D$ model indicates the atomic volume but does not indicate the bond.

How many double bond equivalents (degree of unsaturation) does amoxycillin possess?

State whether the following statements are True or False:
$(i)$ There is a huge number of organic compounds because the carbon atom is very small.
$(ii)$ The number of organic compounds is huge because of catenation.
$(iii)$ Organic compounds are in a huge number because of valency.

Identify the correct order of enol content.