Which of the following is not a isomer of pentane ?

Options

A. n- pentane
B. 2, 2 - dimethyl propane
C. 2, 3- dimethyl butane
D. 2 - methyl butane

Answer

C

Explanation

(a ) ` n` - pentane
` CH_3 - CH_ 2 - CH _2 - CH_ 2 - CH _ 3 " " ( C_5H_12) `
(b) 2, 3 - dimethyl - 1 - propane
` CH _ 3 - overset ( CH _ 3 ) overset (| ) underset ( CH _ 3 ) underset ( | ) C - CH _ 3 " " ( C _ 5 H _ ( 12 ) ) `
(c) 2, 3 - dimethyl - 1 - butane
` CH _ 3- overset ( CH _ 3 ) overset ( |)CH - overset( CH _ 3) overset (|) CH- CH _3 " " ( C _ 6 H _ (14 )) `
(d) 2 methyl - 1-butane
` CH_3 -CH_2 - overset ( CH _ 3) overset (|) CH -CH _ 3 " " (C_5H_(12)) `