The general formula for the alkane series of hydrocarbons is CnH2n+2 The primary amine series has the same saturated structure as the alkanes, but also contains an –NH2 group. What is the general formula for the primary amine series?

Answer:

18) D

Let us take an alkane: Butane. Butane is C₄H₁₀

The -NH₂ group will be joined by taking out an hydrogen atom from the butane.

So the formula would be C₄H₁₁N. This amine has one extra hydrogen atom and one nitrogen atom compared to the original butane.

So the general formula would be CnH2n+3n