. Which of the following is a chemical reaction? A. breaking a glass pane B. freezing water C. digestion of food D. cutting down a tree E. evaporation of rubbing alcohol

C. digestion of food

Explanation:

in a chemical reaction the substance changes composition and the reaction is mostly irreversible.

option C: digestion of food is a chemical reaction which changes the composition of the food we eat. Enzymes and other substances react with the food and turn it into soluble substances which the body can easily use.

option A: breaking glass does not change the composition of the glass plane. Its a physical reaction

option B: freezing water changes the state of water but the composition is still     the same, its a physical reaction as well.

option D: cutting a tree does not change the composition of the wood. This, too, is a physical reaction.

option E: when a liquid evaporates it changes into a gas, which is a change in the state of matter (just like water into ice), this also does not change the composition of alcohol.

answer///multiple alleles;

geologic time scale (for gradpoint) =)