Why is fair weather common during periods of high pressure? (1 paragraph)

If a solution is considered basic, then a) the hydroxide ion and hydronium ion concentrations are equal. b) the hydroxide ion concentration is less than the hydronium ion concentration. c) the hydronium ion concentration is greater than the hydroxide ion concentration. d) the hydroxide ion concentration is greater than the hydronium ion concentration.

How would the number of moles (n) of o2 change if the atmospheric pressure doubled but all other variables stayed the same

One nanometer is equal to how many meters?