Which of the following compounds does $\underline{\text{NOT}}$ contain phantom atoms?

The $IUPAC$ names of $CH_3-CH(OH)-CH_2-C(CH_3)(OH)-CH_3$ and $CH_2(CN)-CH(CN)-CH_2(CN)$ are:

Draw the structures of the following compounds:
$(a)$ $3, 4-$dimethylhexane
$(b)$ $4, 5-$diethyl$-5-$methylnonane
$(c)$ Methylcyclopentane
$(d)$ $1, 3, 5-$triethylcyclohexane
$(e)$ Buta$-1, 3-$diene
$(f)$ Buta$-1, 3-$diyne
$(g)$ Hexa$-1, 3-$diene$-5-$yne

Provide the $IUPAC$ name for the compound: $CH_3-CH(COOH)-CH_2-CH(COOH)-CH(CH_3)-COOH$.

The $IUPAC$ name of the compound $C_2H_5-O-CH(CH_3)_2$ is:

Arrange the following in decreasing order of priority for functional groups of organic compounds:
$(a) -NH_2, -OH, -CN, >C=O, -C \equiv C, >C=C < $
$(b) >C=O, -CHO, -COCl, -COOH, -COOR, -CONH_2, -CN$
$(c) -SO_3H, -CN, -COR, -C \equiv C, >C=C < $