I would say that the density increases because the distance between the molecules decreases, and therefore becomes smaller, and vice versa the density increases, and that is a physical change not a chemical change.
Answer:
HgSO₄
Explanation:
% => g => moles => ratio => reduce => empirical ratio
%Hg = 67.6% => 67.6g/201g/mol = 0.34mol
%S = 10.8% => 10.8g/32g/mol = 0.34mol
%O = 21.6% => 21.6g/16g/mol = 1.35mol
Hg:S:O => 0.34:0.34:1.35
Reduce to whole number ratio by dividing by the smaller mole value...
Hg:S:O => 0.34/.34:0.34/.34:1.35/.34 => Empirical Ratio = 1:1:4
∴ Empirical Formula is HgSO₄