JEE Main Chemistry: Metallurgy High-Yield Practice Questions, Formulas & PYQ Breakdown (2026-27)

Correct Answer: (d)

Explanation: In industry, sulphur dioxide can be prepared by roasting zinc sulphide and iron pyrites. $\begin{aligned} & 2 \mathrm{ZnS}_{(\mathrm{s})}+3 \mathrm{O}_{2(\mathrm{~g})} \stackrel{\Delta}{\longrightarrow} 2 \mathrm{ZnO}_{(\mathrm{s})}+2 \mathrm{SO}_{2(\mathrm{~g})} \\ & 4 \mathrm{FeS}_{2(\mathrm{~s})}+11 \mathrm{O}_{2(\mathrm{~g})} \stackrel{\Delta}{\longrightarrow} 2 \mathrm{Fe}_2 \mathrm{O}_{3(\mathrm{~s})}+8 \mathrm{SO}_{2(\mathrm{~g})} \end{aligned}$

Correct Answer: (a)

Explanation: The given process for extraction of silver is leaching. It is a process of concentration which involves treatment of the ore with a suitable reagent, so as to make it soluble while impurities remains insoluble.

Correct Answer: (a)

Explanation: We are asked about the catalyst used in the reaction: $ \mathrm{CO_{(g)} + H_2O_{(g)} \;\;\xrightarrow{623K}\;\; CO_{2(g)} + H_{2(g)} } $ This is the **water-gas shift reaction**, which is important in industrial hydrogen production. **Catalysts commonly used**: At high temperature (around 623 K to 850 K), the catalyst used is **iron oxide (Fe₂O₃) promoted by chromium oxide (Cr₂O₃)**, generally referred to as **iron chromate catalyst**. At lower temperature (~473 K), catalysts such as Cu-ZnO-Al₂O₃ are used. Now checking the options: **A. Iron chromate → Correct catalyst for high-temperature shift reaction.** B. Vanadium pentoxide → Catalyst for contact process (SO₂ → SO₃). C. Ni metal → Catalyst for hydrogenation reactions. D. Traces of acid or alkali → Used for ester hydrolysis etc. ✅ **Correct answer: Option A — Iron chromate**

Correct Answer: (c)

Explanation: Among the listed options, **stainless steel** is the alloy that has indeed been used in the construction of high-speed aircraft fuselages—famously in aircraft like the Soviet MiG-25 “Foxbat,” which was built largely of stainless steel to withstand high-temperature environments at Mach 3 speeds. Other options: **Nichrome** (nickel–chromium) is primarily used as a heating element due to its high electrical resistance and oxidation resistance, not for fuselage construction. **Cupro-nickel** (copper–nickel) is widely used in marine applications (e.g., ship hulls, coins) because of its corrosion resistance but not in aircraft fuselages. **Bronze** (copper–tin) is traditionally used in bearings, sculptures, etc., not for high-speed aircraft structures. Hence, among the given choices, the correct answer is: **(C) Stainless steel.**

Correct Answer: (c)

Explanation: Iron is made from its ore in a blast furnace. The iron ore has an impurity called $X$. To remove $X$, another chemical, $Y$, is added to the mixture. The chemical $Y$ is calcium carbonate $(\mathrm{CaCO}_3)$. When $Y$ is heated ($\Delta$), it breaks down into calcium oxide $(\mathrm{CaO})$ and carbon dioxide $(\mathrm{CO}_2)$: $ \underset{(Y)}{\mathrm{CaCO}_3} \xrightarrow{\Delta} \mathrm{CaO} + \mathrm{CO}_2 $ Next, calcium oxide $(\mathrm{CaO})$ reacts with the impurity, silicon dioxide $(\mathrm{SiO}_2)$, which is $X$, to form a liquid waste called slag: $ \mathrm{CaO} + \underset{(\text{ Impurity } X)}{\mathrm{SiO}_2} \longrightarrow \underset{(\text{ Slag })}{\mathrm{CaSiO}_3} $ So, $X$ is silicon dioxide $(\mathrm{SiO}_2)$, and $Y$ is calcium carbonate $(\mathrm{CaCO}_3)$.