Fe is made passive by : — d and f Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: Passivity of a metal refers to the loss of its chemical reactivity due to the formation of a thin, non-reactive, protective oxide layer on its surface. Step 2: Concentrated nitric acid (conc. HNO3) is a powerful oxidizing agent that reacts with iron to form a highly protective, impermeable layer of iron oxide (mainly Fe3O4), which prevents further reaction. Step 3: Thus, iron is made passive by concentrated nitric acid, corresponding to option (c).