What is an example of a physical change? having less ash than the paper that was burned to form it ice forming and then melting back into water rust having a different identity than the iron it forms on the irreversible reaction of vinegar and baking soda

Answer;

-Ice forming and then melting back into water

Explanation;

-A physical change is any change in matter that involves the substance going from one physical state to another. The reference to a physical state involves solids, liquids, and gases. When a substance undergoes a physical change it does not lose its original properties when changing from one phase to another.

-Examples of physical changes include;

hydroxyl -oh

alcohols, always polar, can form hydrogen bonds with h2o molecules

carboxyl -cooh  

cargoxylic acids, has acidic properties which is a source of hydrogen ions, found in cells in ionized for with a charge of oh-1

carbonyl > co

ketone if within skeleton, aldehyde if group is at the end of skeleton, k & a may be structural isomers, it determines 2 sugars (ketose & aldose)

amino -nh2

amines, acts as a base, it can pick up h+ ions from surrounding solution, ionized with charge of 1+

methyl ch2

addition to rna/dna affects and gene expression

phosphate -opo3 ²⁻

organic phosphates, contributes to negative charge to, molecule that it is a part of, and potential to react with h20

sulfhydryl -sh

thiols, cross-linking stabilize the protein, and it is structure