Question

General formula of Alkynes is _____.

• A. \(C_nH_{2n+2}\)
• B. \(C_nH_{2n+1}\)
• C. \(C_nH_{2n-2}\)
• D. \(C_nH_{2n}\)

Hint:

Remember: \[ \text{Alkane} \rightarrow C_nH_{2n+2} \] \[ \text{Alkene} \rightarrow C_nH_{2n} \] \[ \text{Alkyne} \rightarrow C_nH_{2n-2} \]

Answer 1

The Correct Option is C

Concept:
Hydrocarbons are organic compounds made up of carbon and hydrogen atoms only. They are classified into:
• Alkanes
• Alkenes
• Alkynes Alkynes are unsaturated hydrocarbons containing at least one triple bond between carbon atoms. The general formula of alkynes is: \[ C_nH_{2n-2} \]

Step 1: Understanding alkynes.
The presence of a triple bond reduces the number of hydrogen atoms in the compound. For example: \[ \text{Ethyne} = C_2H_2 \] Checking the formula: \[ H = 2n - 2 \] For \(n=2\): \[ H = 2(2)-2 \] \[ H = 4-2 \] \[ H = 2 \] Thus, \[ C_2H_2 \] which matches the alkyne formula.

Step 2: Comparing with other hydrocarbon formulas.

• Alkanes: \[ C_nH_{2n+2} \]
• Alkenes: \[ C_nH_{2n} \]
• Alkynes: \[ C_nH_{2n-2} \] Therefore, the correct answer is: \[ \boxed{(3)\ C_nH_{2n-2}} \]