Mr[Mg(OH)2] = Ar[Mg] + Ar[O] * 2 + Ar[H] * 2 = 24 + 16 * 2 + 1 * 2 = 58
Mr[HNO3] = Ar[H] + Ar[N] + Ar[O] * 3 = 1 + 14 + 16 * 3 = 63
Объяснение:
