Question

The structures of four hydrocarbons are shown below:

\[\begin{array}{cc} \phantom{.....}\ce{CH3}\\ \phantom{...}|\\ \ce{H3C - C - H}\\ \phantom{...}|\\ \phantom{.....}\ce{CH3} \end{array}\]

\[\begin{array}{cc} \ce{CH3}\phantom{.....}\\ |\phantom{.......}\\ \ce{C = CH2}\\ |\phantom{.......}\\ \ce{CH3}\phantom{....} \end{array}\]

\[\begin{array}{cc} \ce{H}\phantom{.....}\\ |\phantom{.....}\\ \ce{H3C - C - C = CH2}\\ |\phantom{....}|\\ \ce{H\phantom{...}H} \end{array}\]

\[\begin{array}{cc} \phantom{...}\ce{CH3}\\ |\\ \ce{H3C - C = CH2} \end{array}\]

How many isomers of butene are shown in the above structures?

विकल्प

• 1

• 2

• 3

• 4

Answer 1

2

Explanation:

Structure 1 is 2-methylpropane (C₄H₁₀), an alkane, not a butene isomer.

Structure 2 is 2-methylpropene (CH₂ = C(CH₃)₂), which is a butene isomer.

Structure 3 is but-1-ene (CH₂ = CH − CH₂ − CH₃), which is also a butene isomer.

Structure 4 is a repeat representation of structure 2 (2-methylpropene). 

Therefore, there are only two unique butene isomers visually represented among the four drawings.