Question

Which of the following is not a pair of functional isomers?

• A. CH₃COOH and HCOOCH₃
• B. C₂H₅OC₂H₅ and C₃H₇0CH₃
• C. CH₃CH₂OH and CH₃OCH₃
• D. CH₃CH₂NO2 and H₂NCH₂COOH

Answer 1

The Correct Option is B

Functional isomers are compounds that have the same molecular formula but different functional groups.
1. Option (A): \( \text{CH}_3\text{COOH} \) is acetic acid (carboxylic acid), and \( \text{HCOOCH}_3 \) is methyl formate (ester). These are functional isomers because they have different functional groups: carboxylic acid and ester.
2. Option (B): \( \text{C}_2\text{H}_5\text{OC}_2\text{H}_5 \) is ethyl ether, and \( \text{C}_3\text{H}_7\text{OCH}_3 \) is methoxypropane. These compounds are not functional isomers; they have different molecular formulas and hence are not functional isomers.
3. Option (C): \( \text{CH}_3\text{CH}_2\text{OH} \) is ethanol (alcohol), and \( \text{CH}_3\text{OCH}_3 \) is dimethyl ether (ether). These are functional isomers because they have the same molecular formula but different functional groups: alcohol and ether.
4. Option (D): \( \text{CH}_3\text{CH}_2\text{NO}_2 \) is nitroethane, and \( \text{H}_2\text{NCH}_2\text{COOH} \) is glycine. These are functional isomers because they have different functional groups: nitro group and amino acid group. Thus, the correct answer is (B), as \( \text{C}_2\text{H}_5\text{OC}_2\text{H}_5 \) and \( \text{C}_3\text{H}_7\text{OCH}_3 \) are not functional isomers.

The correct option is (B): \(C_2H_5OC_2H_5\) and \(C_3H_7OCH_3\)

Answer 2

Functional isomers are compounds that have the same molecular formula but differ in the functional groups they contain. Now, let's examine the options:

• Option (A): \( \text{CH}_3\text{COOH} \) (acetic acid) and \( \text{HCOOCH}_3 \) (methyl formate) are functional isomers because both have the same molecular formula \( \text{C}_2\text{H}_4\text{O}_2 \) but differ in their functional groups: carboxyl group \( \text{-COOH} \) and ester group \( \text{-COO-} \).
• Option (B): \( \text{C}_2\text{H}_5\text{OC}_2\text{H}_5 \) (diethyl ether) and \( \text{C}_3\text{H}_7\text{OCH}_3 \) (methyl ethyl ether) do not have the same molecular formula. They differ in the number of carbon atoms and therefore are not functional isomers.
• Option (C): \( \text{CH}_3\text{CH}_2\text{OH} \) (ethanol) and \( \text{CH}_3\text{OCH}_3 \) (dimethyl ether) are functional isomers because both have the same molecular formula \( \text{C}_2\text{H}_6\text{O} \) but differ in their functional groups: alcohol group \( \text{-OH} \) and ether group \( \text{-O-} \).
• Option (D): \( \text{CH}_3\text{CH}_2\text{NO}_2 \) (nitroethane) and \( \text{H}_2\text{NCH}_2\text{COOH} \) (glycine) are functional isomers because both have the same molecular formula \( \text{C}_2\text{H}_5\text{NO}_2 \) but differ in their functional groups: nitro group \( \text{-NO}_2 \) and amino group \( \text{-NH}_2 \).

Thus, Option (B) is the correct answer because the two compounds do not have the same molecular formula and therefore cannot be functional isomers.