Chemistry assignment multiple choice:(

someone please help!!!
i will give a brainist:)

18. use the activity series to predict whether the following synthesis reaction will occur. write the chemical equations for the reaction if it's predicted to occur. (s) + o2(g) -> *note: it is possible.*

This image is an example of a(n) a) atom. b) compound. c) mixture. d) molecule.

The twister and runaway train are two coasters at the same amusement park. both coasters start at the same height. the coaster for the twister is twice the mass of the coaster for the runaway train. which roller coaster has greater gravitational potential energy at the start of the ride?