Question

Chemical reactions can be detected by precipitation of a _____ from a solution.

solid enzyme activation complex

Answer 1

For sure, the answer isn't activation complex because I got that wrong. It is solid. 

Answer 2

Answer: solid

Explanation: Chemical reactions are those which involve rearrangement of atoms.

Chemical changes are accompanied by following changes:

1) Absorption or release of heat

2) Change in color

3) Formation of gas bubbles

4) Formation of a solid product called as precipitate

Example of formation of precipitate or solid in chemical reaction:
`2AgNO_3(aq)+BaCl_2(aq)\rightarrow 2AgCl(s)+Ba(NO_3)_2(aq)`