$CH_3CH_2CH_2CH_2CH_2CH_3$ $(CH_3)_3 CCH_2CH_3$
$(CH_3)_2CHCH_2CH_2CH_3$ $(CH_3)_2CHCH(CH_3)_2$
$2$ -ethyl butane is incorrect name.$CH_3 CH_2 CH=CH_2 \xrightarrow{{HBr/{H_2}{o_2}}}\,Y\,\xrightarrow{{{C_2}{H_5}ONa}}Z$


