Which of the following compounds does not contain a polyatomic ion? A -sodium carbonate
B-sodium sulfate
C- sodium sulfite
D- sodium sulfide

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

answer; capital earns interest; entrepreneurship receives a profit or incurs a loss;