Which statement describes all chemical changes, but not all physical changes?

Which diagram shows the correct way to represent an ionic compound of magnesium oxide?

When hydrochloric acid reacts with potassium hydroxide solution, the following reaction occurs. hcl (aq) + koh (aq) h2o (l) + kcl (aq) the reaction gives off heat energy, so it is an reaction.

Answer asap need by wednesday morning calculate the ph of 0.16m ch3cooh which has ka = 1.74 x 10-5 mol dm-3 best answer will be brainliest