Answer:
Carbohydrates are polyhydroxy aldehydes, ketones, or compounds that yield polyhydroxy aldehydes or ketones upon hydrolysis. FALSE
Monosaccharides exist as cyclic structures containing functional groups such as hydroxyl groups, acetal (ketal), and hemiacetal (hemiketal). TRUE
A carbohydrate can be classified as a monosaccharide, disaccharide, or polysaccharide TRUE
Disaccharides exist as cyclic structures that only contain hemiacetal (or hemiketal) groups. FALSE
Explanation:
carbohydrates consists of a long cyclic chain of monosaccharides. They are polysaccharides and exist in the cyclic structure. It is only the individual monosaccharides that contain the aldehyde or ketone group as the case may be.
When completely hydrolysed monosaccharides are formed from polysaccharides which are cyclic hemiacetals and acetals containing the hydroxyl functional group.
Carbohydrates containing only one sugar unit is a monosaccharide, if it contains two sugar units it is a diasaccharide, it contains more than two sugar units it is a polysaccharide.
Diasaccharides such as fructose also contain hemiacetal or hemiketal groups and -OH groups also.
