What are 4 indicators that a chemical reaction has occurred?

Iknow #2 is d. i just need to know why

Aphysical reaction is a process in which one or more reactants change into one or more products with different properties. select the best answer from the choices provided t f

If you add 5.00 ml of 0.100 m sodium hydroxide to 50.0 ml of acetate buffer that is 0.100 m in both acetic acid and sodium acetate, what is the ph of the resulting solution? acetic acid: ka = 1.8. x 10-5