Which of these correctly defines the poh of a solution?

The correct answer is:

The negative log of the hydroxide ion concentration.

Explanation:

The pOH is a standard of hydroxide ion (OH-) concentration. pOH is a step of the alkalinity of a solution. Aqueous solutions at 25°C with pOH less than 7 are alkaline, pOH greater than 7 are acidic and pOH equal to 7 are neutral.pOH scale can be determined as follows

pOH = -log[OH⁻]

[OH⁻] is the hydroxide ion concentration,therefore pOH is the negative log of the hydroxide ion concentration

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.