Select the statement that is incorrect.
complex sugars are carbohydrates.
all carbohydrates have the general formula cn(h2o)n.
simple sugars are carbohydrates.
simple sugars contain only carbon, oxygen, and hydrogen atoms.

The 3rd sentence is the wrong one:

'All carbohydrates have the general formula Cn(H2O)n'

Explanation:

This is wrong because it's a formula that holds true for simple sugars, but not for complex ones.

Take sucrose as an example, its formula is C12H22O11. Clearly it's C12(H2O)11.

This is so, because when a glycosidic bond is formed, it does so with the loss of a water molecule; hence the reaction is called condensation.