Which of the following equations represents an addition reaction?

• A. $C{H}_3-C{H}_{2}OH\to C{H}_2=C{H}_2+H$₂O
• B. $C{H}_{3}Cl+KOH\to C{H}_2=C{H}_2+KCl+H{2}_{2}O$
• C. $C{H}_4+O{2}_2\to CO{2}_2+H{2}_{2}O$
• D. $C{H}_2=C{H}_2+H{H}_2\to C{H}_3-C{H}_3$

Answer: (D)

Verified step by step guidance

1. Step 1: Understand what an addition reaction is. In organic chemistry, an addition reaction involves two reactants combining to form a single product without any atoms being lost. Typically, this occurs with molecules containing double or triple bonds, where the multiple bond is broken and new single bonds are formed.
2. Step 2: Analyze each given equation to identify whether it fits the criteria of an addition reaction. Look for a reactant with a double or triple bond and check if the product has that bond replaced by single bonds with added atoms.
3. Step 3: For the first equation, observe that it shows an alcohol converting into an alkene and water. This is a dehydration reaction, which is an elimination reaction, not an addition.
4. Step 4: For the second equation, note that it involves an alkyl halide reacting with potassium hydroxide to form an alkene, potassium chloride, and water. This is a substitution or elimination reaction, not an addition.
5. Step 5: For the third equation, check if a molecule with a double bond reacts with another molecule (like H2) to form a saturated molecule. This fits the definition of an addition reaction, where the double bond is broken and atoms are added across it.