Question

Explain the following

1. Reactivity of Aluminum$\left(\mathrm{Al}\right)$ decreases, if it is dipped in Nitric acid$\left({\mathrm{HNO}}_3\right)$
2. Carbon$\left(\mathrm{C}\right)$ cannot reduce the oxides of Sodium $\left(\mathrm{Na}\right)$or Magnesium$\left(\mathrm{Mg}\right)$
3. Sodium chloride$\left(\mathrm{NaCl}\right)$ is not a good conductor of electricity in solid state whereas it does conduct electricity in Aqueous state as well as in molten state
4. Iron$\left(\mathrm{Fe}\right)$ articles are galvanized
5. Metals like Sodium$\left(\mathrm{Na}\right)$, Potassium$\left(\mathrm{K}\right)$, Calcium$\left(\mathrm{Ca}\right)$, Magnesium$\left(\mathrm{Mg}\right)$ are never found in their free state in nature.

Answer 1

Reactivity of Metals

1. Reactivity of Aluminum$\left(\mathrm{Al}\right)$-When Aluminum$\left(\mathrm{Al}\right)$ is dipped in Nitric acid$\left({\mathrm{HNO}}_3\right)$ a layer of Aluminium oxide $\left({\mathrm{Al}}_2{\mathrm{O}}_3\right)$is formed on the metal due to the strong oxidizing nature of acid. The formed layer of Aluminium oxide $\left({\mathrm{Al}}_2{\mathrm{O}}_3\right)$ prevents further reaction and reactivity of Aluminium decreases.
2. Reactivity of Carbon$\left(\mathrm{C}\right)$- In the reactivity series, Sodium$\left(\mathrm{Na}\right)$ and Magnesium$\left(\mathrm{Mg}\right)$ are above Carbon which implies Carbon is less reactive .So it cannot reduce Sodium $\left(\mathrm{Na}\right)$and Magnesium$\left(\mathrm{Mg}\right)$.
3. Reactivity of Sodium chloride$\left(\mathrm{NaCl}\right)$-In solid state movement of ions is not possible due to rigid structure. Sodium chloride is a solid.Hence it is not reactive whereas movement of ions is causes electricity which make aqueous solution and molten stage of Sodium Chloride to become reactive.
4. Iron$\left(\mathrm{Fe}\right)$ are galvanised- Galvanization is the process of coating Zinc$\left(\mathrm{Zn}\right)$ over Iron$\left(\mathrm{Fe}\right)$ or steel to prevent rusting. The formed layer of Zinc oxide$\left(\mathrm{ZnO}\right)$ prevents the corrosion.
5. Nature of Metals like Sodium$\left(\mathrm{Na}\right)$, Potassium$\left(\mathrm{K}\right)$, Calcium$\left(\mathrm{Ca}\right)$, Magnesium$\left(\mathrm{Mg}\right)$ in free state-They are highly reactive metals.They reacts with Oxyen even in room temperature forming metal oxides.

Hence this metal cannot be in free state