Question

But-2-ene and but-1-ene are ________ isomers.
(a)- Positional
(b)- Functional
(c)- Geometrical
(d)- Chain

Answer 1

In chemical compounds, there is a phenomenon of isomerism in which different compounds have a different structural formula but have the same chemical formula, and such compounds are called isomers. Based on the positions there are positional isomers, based on the chain arrangement they are chain isomers, etc.

Complete step-by-step answer: In chemical compounds, there is a phenomenon of isomerism in which different compounds have a different structural formula but have the same chemical formula, and such compounds are called isomers.
Based on the positions of the functional group on the carbon chain they are positional isomers, based on the chain arrangement they are chain isomers, based on a different functional group they are functional isomers when the same compound can be written in a cis and trans form then it is geometrical isomers.
But-1-ene is an organic compound having four carbon atoms and at the first carbon, there is a double bond present. Its structure is given below:
$C{{H}_{2}}=CH-C{{H}_{2}}-C{{H}_{3}}$
But-2-ene is an organic compound having four carbon atoms and at the second carbon, there is a double bond present. Its structure is given below:
$C{{H}_{3}}-CH=CH-C{{H}_{3}}$
So, the molecular formula for both the compounds is ${{C}_{4}}{{H}_{8}}$, but the position of the double bond is different. So, they are the example of positional isomerism and they are position isomers.

Therefore, the correct answer is an option (a)- Position.

Note: Other examples of positional isomers in which there is a different position of the functional group are butan-2-oic acid and butan-3-oic acid, pentan-2-ol and pentan-3-ol, etc.