Which of the following compounds contains an isopropyl group?

The $IUPAC$ name of the following compound is:

The $IUPAC$ name of the following compound is:

Give the general formula of alkyl group with examples up to four carbon.

Write $IUPAC$ names of the following compounds:
$(i)$ $(CH_3)_2CH-CH=CH-CH_2-CH=C(CH_3)-CH(C_2H_5)-CH_3$
$(ii)$ The structure is shown below:
$(iii)$ $CH_2=C(CH_2CH_2CH_3)_2$
$(iv)$ $CH_3-CH(CH_3)-CH=C(C_2H_5)-CH_2-CH(CH_3)-CH_2CH_2CH_3$

Select the correct $IUPAC$ name of pyrogallol.