Which substance is the least likely to dissolve in water?
a. methanol (polar)
b. methane (gas)
c. vegetable oil (nonpolar)
d. table salt (ionic)

Vegetable oil

Explanation:

because it is nonpolar object

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.