The alkyl group is represented by the general formula

1. Analyze the question You are asked for the general formula of an alkyl group (such as methyl, ethyl, propyl).

2. Explain the concept An alkyl group is formed when one hydrogen atom is removed from an alkane. It is not a complete molecule. It is a fragment that attaches to another atom or group.

• Alkanes: CnH2n+2
• Remove one H, and you get the alkyl group: CnH(2n+2−1) = CnH2n+1

3. Step-by-step solution

| Alkane | Formula | Alkyl group | Formula | |---|---|---|---| | Methane | CH₄ | Methyl | CH₃ | | Ethane | C₂H₆ | Ethyl | C₂H₅ | | Propane | C₃H₈ | Propyl | C₃H₇ |

Check with n = 1: 2(1) + 1 = 3, so CH₃ ✔ Check with n = 2: 2(2) + 1 = 5, so C₂H₅ ✔ Check with n = 3: 2(3) + 1 = 7, so C₃H₇ ✔

Why the other options are wrong:

• A. CnH2n is the general formula for alkenes (and cycloalkanes).
• B. CnH2n−2 is the general formula for alkynes (and alkadienes).
• D. CnH2n+2 is the general formula for alkanes.

4. Answer The correct option is C. CnH2n+1.

5. Exam tip Remember: Alkane − 1 H = Alkyl. Start with CnH2n+2 and subtract one hydrogen. Also, the name changes from "-ane" to "-yl" (methane → methyl, ethane → ethyl).