а) Mr(MgS) = 24 + 32 = 56.
б) Mr(Na3) = 23 * 3 = 69.
в) Mr(K2CO3) = 39 * 2 + 12 + 16 * 3 = 138.
г) Fe(OH)3 = 56 + 16 * 3 + 1 * 3 = 107.
а) Mr(MgS) = 24 + 32 = 56.
б) Mr(Na3) = 23 * 3 = 69.
в) Mr(K2CO3) = 39 * 2 + 12 + 16 * 3 = 138.
г) Fe(OH)3 = 56 + 16 * 3 + 1 * 3 = 107.