How do you read the periodic table

In which layer of earth do most earthauakes occur a_ inner core b_outer core c_mantle d_crust

Which best describes the present-day universe? opaque, expanding very slowly, stars produce heavy elements transparent, expanding at an accelerated rate, stars produce heavy elements opaque, expanding at an accelerated rate, stars produce only hydrogen and helium transparent, expanding very slowly, stars produce only hydrogen and helium

Ireally need ! calcium metal reacts with a potassium chloride solution to form calcium chloride and potassium ions. balance this reaction. (s) + (aq) → cacl2(s) + +(aq) a) 1, 2, 1, 2 b) 1, 2, 1, 1 c) 1, 1, 1, 1 d) 2, 1, 2, 1