Metallurgy, Metals, Non-Metals & Alloy RRB PYQ

Calcium (Ca) is the most reactive element among the given options. As an alkaline earth metal, calcium has high reactivity, especially with water and oxygen, where it forms calcium hydroxide and hydrogen gas. Compared to other elements listed, calcium reacts more vigorously, making it more reactive than lead (Pb), magnesium (Mg), and aluminum (Al).

The main purpose of refining a metal after it has been extracted is to remove impurities from the extracted metal. Metals extracted from their ores using standard reduction processes are often in an impure state known as crude metal. These crude metals contain various impurities, such as other metals, non-metals like carbon, silicon, or sulphur, or leftover slag. Common refining methods include electrolytic refining, zone refining, liquation and distillation.

The reactivity series ranks metals by their tendency to lose electrons. Potassium (K) is the most reactive, followed by aluminum (Al). Iron (Fe) is next, then lead (Pb), and gold (Au) is the least reactive. Hence, the order is: K > Al > Fe > Pb > Au.

Sodium is placed highest among the given metals and it reacts vigorously with water and oxygen. Sodium is an alkali metal (Group 1) with one valence electron, which it 'wants' to lose urgently to become stable. However, the metal placed highest in the standard reactivity series is Potassium (K) due to very low ionization energy. Other reactive metals are Caesium, Francium, Rubidium, Lithium, Calcium, and Magnesium.

Galvanisation protects iron from rusting by coating it with a thin layer of Zinc metal only. Galvanisation is the process of applying a protective zinc coating to iron or steel to prevent rusting. The zinc layer creates a physical barrier that prevents moisture and oxygen from reaching the underlying iron. Zinc is more reactive than iron. If the coating is scratched, the zinc acts as a sacrificial anode, meaning it corrodes in place of the iron to protect the exposed metal. While galvanisation is a common and effective method for protecting iron, several other techniques are used such as alloying and electroplating.

The blue colour of copper sulphate solution fades when an iron nail is dipped in it because copper sulphate is converted into iron sulphate. This is a classic example of a Single Displacement Reaction. Because iron is more reactive than copper, it displaces copper from its salt solution. Chemical Equation: Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s). The original blue colour is due to Cu2+ ions in the copper sulphate solution. As the reaction proceeds, these ions are replaced by Fe2+ ions, forming Ferrous Sulphate (FeSO4), which is light green in colour. This causes the blue to fade. Beyond the fading liquid, you will see a reddish-brown coating of copper metal depositing on the surface of the iron nail.

An electrolyte used during the refining of metals by electrolysis must be an aqueous or molten solution of a suitable metal salt. For electrolysis to occur, the electrolyte must contain free-moving ions. In solid form, ions are held in a fixed lattice; therefore, the salt must be dissolved in water or melted to allow these ions to migrate toward the electrodes. In electrolytic refining, the electrolyte is typically a solution of the same metal being refined. This ensures that metal ions can be consistently transferred from the impure anode to the pure cathode. The Cathode Reaction: During the process, metal ions from the electrolyte are reduced (gain electrons) at the negative cathode, where they deposit as pure metal: Cu2+ + 2e- → Cu (pure metal).

When a magnesium ribbon burns in the air, it reacts with oxygen to form a white substance called magnesium oxide (MgO). The chemical reaction is: 2Mg + O2 → 2MgO. Magnesium oxide is a white powder that is formed after the combustion of magnesium, which burns with a bright, dazzling flame.

In the reaction Fe2O3 + 3CO → 2Fe + 3CO2, carbon monoxide (CO) acts as the reducing agent. CO reduces ferric oxide (Fe2O3) to iron (Fe) by donating electrons and gets oxidized to CO2 in the process. A reducing agent loses electrons and causes the other substance to be reduced.

In the reaction ZnO + C → Zn + CO, ZnO is reduced to Zn, as it gains electrons and the oxidation state of zinc decreases from +2 to 0. Carbon acts as a reducing agent and is oxidized to carbon monoxide (CO), where its oxidation state increases from 0 to +2. This is a redox reaction involving both reduction and oxidation.