How many neutrons does an element have if its atomic number is 42 and its mass number is 155? (10 points)

What diagram shows the ionic compound of magnesium oxide

Light waves can move through , but they travel fastest when they move through a(n) .

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)