Fructose forms: a. a five-membered cyclic hemiacetal. b. a six-membered cyclic hemiacetal. c. a six-membered lactone. d. a five-membered lactone. e. none of these

A. a five-membered cyclic hemiacetal.

Explanation:

Fructose is a hexose sugar with a ketone group unlike glucose which has an aldehyde group.

The fructose also forms a cyclic structure due to formation of hemiacetal bond however unlike glucose the cyclic structure formed is a five membered ring.

The hemiacetal bond is formed when an alcohol reacts with a carbonyl group.

The structure of fructose is shown in the figure.

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.