What is the $IUPAC$ name of the given compound?

What is the $IUPAC$ name of the following compound?
$\begin{array}{c} H \\ | \\ CH_3-C=C-CH_3 \\ | \\ CH_2CH_3 \end{array}$

The $IUPAC$ name of $CH_3-C(CH_3)(OH)-CH_2-CH(OH)-CH_3$ is

The $IUPAC$ name for the following compound is $BrCH_2-CH_2-CH=CH-CH_2-CO-CH_3$.

Which of the following groups is selected as the principal functional group for the nomenclature of a polyfunctional compound according to the $IUPAC$ system?

Give the $IUPAC$ names of the following compounds:
$(i)$ $Ph-CH_2-CH_2-COOH$
$(ii)$ $(CH_3)_2C=CH-COOH$
$(iii)$ Structure of $2-$Methylcyclopentanecarboxylic acid
$(iv)$ Structure of $2,4,6-$Trinitrobenzoic acid