Question
# The general formula of carbohydrates is:A.${C_n}{H_{2n + 1}}O$B.${C_n}{H_{2n}}O$C.${C_n}{({H_2}O)_n}$D.${C_n}{({H_2}O)_{2n}}$
Hint: Glucose is one of most important carbohydrates having the structural formula ${C_6}{H_{12}}{O_6}$. Its simplest or empirical formula comes out to be $C{H_2}O$.
The empirical formula of a carbohydrate comes from the fact that a carbohydrate is a biomolecule consists of carbon(C), hydrogen(H) and oxygen(O) atoms, with a hydrogen-oxygen atom ratio of 2:1 and the ratio of carbon to hydrogen to oxygen is 1:2:1. So we can refer to it as carbon water or hydrates of carbon and represent it as ${(C{H_2}O)_n}$, where n can be any number greater than 3. Therefore, it can also be written as ${C_n}{({H_2}O)_n}$. This formula explains the meaning of the term ‘carbohydrate’ i.e. the components are carbon for carbon and water for hydrate. The simplest carbohydrate thus formed by putting n as 1 is glucose, ${C_6}{H_{12}}{O_6}$.
This general formula has many exceptions. For example, acetic acid ($C{H_3}COOH$) will fit in the general formula described for carbohydrates but it is not a carbohydrate. Similarly, formaldehyde (HCHO) is not a carbohydrate yet falls under this category.