Well they're both mercury chloride. The first is mercury (I) chloride, while the second is mercury (II) chloride, mercury dichloride or mercuric chloride. I don't know anything about their chemical or physical properties.
what is the answer to this please: try writing equations for these reactions: Hydrogen + copper (II) oxide ->>>>> copper + water. Is it CuO2 + H >>>> Cu + water ( forget about balancing for now)