The reference compound $iso$-octane,which is used in determining the octane number of gasoline,has the structure:

The $IUPAC$ name of $(C_2H_5)_2N-CH_2-CH(Cl)-COOH$ is:

The $IUPAC$ name of succinic acid is:

Select the structure with the correct numbering for the $IUPAC$ name of the compound.

Write $IUPAC$ names and calculate the number of $\sigma$ and $\pi$ bonds for the following compounds:
$(i)$ $CH_3-CH(CH_3)-CH=CH-CH_2-CH=C(CH_3)-CH_2-CH_3$
$(ii)$ $CH_3-CH=CH-CH_2-CH=CH-CH(C_2H_5)-CH_2-CH_3$
$(iii)$ $CH_2=C(CH_2-CH_2-CH_3)_2$
$(iv)$ $CH_3-CH(C_4H_9)-CH=C(C_2H_5)-CH_2-CH(CH_3)_2$

For each of the following compounds,write a condensed formula and also their bond-line formula.
$(a)$ $HOCH_{2}CH_{2}CH_{2}CH(CH_{3})CH(CH_{3})CH_{3}$
$(b)$ $N \equiv C-CH(OH)-C \equiv N$