A primary amide is generally represented by the formula

Correct answer: RCONH₂

Explanation: Amides have the acyl group –CON–. A primary amide has two hydrogens on the nitrogen: –CONH₂. A secondary amide is RCONHR and a tertiary amide is RCONR₂. RCOOR is an ester, not an amide.

• RCOOR — Ester (wrong).
• RCONH₂ — Correct (primary amide).
• RCONHR — Secondary amide (wrong).
• RCONR₂ — Tertiary amide (wrong).