(chemistry) a chemical reaction

(pharmacology) reagent

to investigate, to look up, to look into, to study, to examine, to check up on, to look over / (music) to play, to perform (an instrument) / (music) to tune

to use / to employ / to make use of, to apply / to spend

chemistry (branch of natural science)

to react chemically / to respond, to react / be responsive, be sensitive

chemical reaction / reaction, response / feedback

chemistry (branch of natural science)

to use one's head

use one thing for many purposes / work someone hard