Which equation states Newton's second law

A. A=m^2/F
B. A=Fm
C. A=F/m
D. A=m/f

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?

The msds for glacial acetic acid says that it is a flammable liquid that can severely burn any human tissue it comes in contact with. it reacts with bases, various metals, and strong oxidizing agents. its vapors can form explosive mixtures with air.

Air can be considered a mixture. which statement does not explain why?