4. В каком ряду представлены простые вещества-металлы:

Metals are elements that tend to lose electrons. Option (a) sulfur, nickel, silver includes non-metals and metals. Option (b) diamond, sulfur, calcium includes non-metals and a metal. Option (c) potassium, barium, lithium are all alkali and alkaline earth metals, hence they are metals. Option (d) hydrogen, ozone, nitrogen are non-metals.