Is h2o a polar or non polar compound?

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

Find the mass, in grams, of 5.00*10^23 molecules of f2

Insoluble sulfide compounds are generally black in color. which of the following combinations could yield a black precipitate? check all that apply. na2s(aq)+kcl(aq) li2s(aq)+pb(no3)2(aq) pb(clo3)2(aq)+nano3(aq) agno3(aq)+kcl(aq) k2s(aq)+sn(no3)4(aq)