What is the common formula for the alkanes?

Correct option is B

Explanation of the Correct Option (b): CₙH₂ₙ₊₂
· Alkanes are saturated hydrocarbons.
· They contain:
· Only single covalent bonds between carbon atoms
· No double or triple bonds
· Each carbon atom forms four bonds (tetravalency).
· Due to complete saturation, the general molecular formula becomes:
· CₙH₂ₙ₊₂
· Examples:
· Methane (CH₄) → n = 1
· Ethane (C₂H₆) → n = 2
· Propane (C₃H₈) → n = 3
Explanation of Other Options
Option (a): CₙH₂ₙ
· Incorrect because:
· This is the general formula for alkenes (one double bond).
Option (c): CₙH₂ₙ₋₂
· Incorrect because:
· Represents alkynes (one triple bond) or cyclic compounds.
Option (d): CHₙ
· Incorrect because:
· Not a valid general formula for hydrocarbons.
Key Points Related to the Question
· Alkanes = saturated hydrocarbons
· General formula: CₙH₂ₙ₊₂
· First member: Methane (CH₄)
· Known as paraffins