Common oxidation states of mercury are 1 and 2. in the 1 oxidation state, mercury forms a diatomic cation. in the 2 oxidation state, mercury is a typical monatomic cation.

The question is asking to calculate and give the formulas for the mercury bromide, base on my research, the answer would be HgBr, I hope you are satisfied with my answer and feel free to ask for more if you have questions and further clarifications 

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .