10 points which can happen during a physical change?

a) molecules can move more rapidly and freely and change states.
b) the molecules in a substance break into smaller molecules.
c) the molecules in a substance react with other molecules.
d) the molecules in a substance are destroyed.

i know it's not c or d, i'm not sure if b would count as a physical change or not.

Silver tarnishes as silver metal reacts with hydrogen sulfide, h2s, in the air. in this reaction, dark silver sulfide, au2s, covers the surface of silver. when silver is polished, this coating of silver sulfide can be removed from the surface. this makes the silver shiny again. enter the coefficients that balance the tarnishing reaction equation. (type 1 for no coefficient.)

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

What is the mass of 0.46 mol of mgcl2