Question

Which of the following shows addition reaction?

• A. \(CH_4\)
• B. \(C_3H_8\)
• C. \(C_2H_6\)
• D. \(C_2H_4\)

Hint:

Alkenes and alkynes undergo addition reactions because of the presence of multiple bonds. Alkanes mainly undergo substitution reactions.

Answer 1

The Correct Option is D

Step 1: Know what an addition reaction needs.
An addition reaction can only happen when there is a double or triple bond between carbon atoms. Such compounds are called unsaturated.

Step 2: Check the first three options.
$CH_4$ is methane, $C_2H_6$ is ethane, and $C_3H_8$ is propane.

Step 3: See that these are saturated.
All three of them have only single bonds between carbons. They belong to the alkane family and are saturated, so they do not add atoms easily.

Step 4: Look at the last option.
$C_2H_4$ is ethene. It has a carbon-carbon double bond: \[ CH_2 = CH_2 \]

Step 5: Show why it adds.
The double bond can open up and let new atoms join. For example hydrogen adds across it: \[ C_2H_4 + H_2 \rightarrow C_2H_6 \]

Step 6: Choose the answer.
The compound that shows an addition reaction is $C_2H_4$. \[ \boxed{C_2H_4} \]