Answer:
Chemical, cause physical are changes affecting the form of a chemical substance, but not its chemical composition. This doesn't affect the substance but the composition.
Explanation:
In amides, the carbonyl carbon is bonded to a nitrogen. The nitrogen in an amide can be bonded either to hydrogens, to carbons, or to both. ... Another way of thinking of an ester is that it is a carbonyl bonded to an alcohol. Thioesters are similar to esters, except a sulfur is in place of the oxygen.
A. They speed up chemical reactions
