Which of the following is incorrect?

Options

A. Carbohydrates are composed of the elements: carbon, hydrogen and oxygen
B. The general formula of most of the carbohydrates is `C_(n)(H_(2)O)_(m)`
C. `C_(2)H_(4)O_(2)` represents a carbohydrates
D. The minimum number of carbon atoms that should be present in a carbohydrate is 3.

Answer

C

Explanation

`C_(2) H_(4)O_(2)` is actually a carboylic acid, called 'acetic acid, `CH_(3) COOH`. The general formula for most of the carbohydrates is `C_(n) (H_(2) O)_(m)`. This formula, with carbo for carbon and hydrate for `H_(2)O`, accounts for the name carbohyrates. For simple carbohydrates, `n = m`.
Carbohydrates are commonly defined, in a limited sense, as polyhydroxy adehydes or ketones that have on `OH` bonded to each `C` other than the `C== O`. Thus, there are two functional groups `(gt C == O` and `OH`) which are present in typical carbohydrates.
The simplest monosaccharide is glycolaldehyde, `HOCH_(2)CHO`, It is optically inactive. it is more appropriate to exclude glycoladehyde from the group of sugars as we usually define sugar optically active polyhydroxy aldehydes or ketones.