Question

The general formula of alkanes is:
(A) $$C_n{H}_{2n}$$
(B) $$C_n{H}_{2n-2}$$
(C) $$C_n{H}_{2n+2}$$
(D) $$C_n{H}_{2n+1}$$

Answer 1

Hint: Try to recall that alkanes are acyclic saturated hydrocarbons containing a carbon-carbon and carbon-hydrogen single bonds. Each carbon atoms in alkanes are $$s{p}^3$$-hybridized. Now, by using this you can easily find the correct option from the given options.
Complete step by step solution:
* It is known to you that alkanes are acyclic saturated hydrocarbons and contain only carbon-carbon and carbon-hydrogen single bonds.
Alkanes do not show geometrical isomerism because they are tetrahedral in shape.
* Also, it is known that propane is the third member of the alkane series. The chemical formula of propane is $$C_3{H}_8$$.
* Now, since the chemical formula of propane is known to you and also, it is known that propane is the first member of the alkane series. So, you can easily find the general formula of alkanes by inspecting each option by putting the value of n =1.
Option A: On putting the value n=3 in $$C_n{H}_{2n}$$, we get the chemical formula $$C_3{H}_6$$. So, option A is not the correct option and this is the general formula of alkenes.
Option B: On putting the value n=3 in $$C_n{H}_{2n-2}$$, we get the chemical formula $$C_3{H}_4$$. So, option B is also an incorrect option and this is the general formula of alkynes.
Option C: On putting the value n=3 in $$C_n{H}_{2n+2}$$, we get the chemical formula $$C_3{H}_8$$. So, option C is the correct option and this is the general formula of alkanes.
Option D: On putting the value n=3 in $$C_n{H}_{2n+1}$$ we get the chemical formula $$C_3{H}_7$$. So, option D is also not the correct option.
Hence, from above we can easily say that option C is the correct option to the given question.
Note:
* It should be remembered that higher alkanes in the form of gasoline, kerosene oil, diesel, lubricating oils and paraffin wax are widely used.
* Also, you should remember that catalytic oxidation of alkanes gives alcohols, aldehydes and carboxylic acids.