Industrial Chemistry — Set 3
Chemistry · औद्योगिक रसायन · Questions 21–30 of 40
Which metal is the best conductor of electricity?
Correct Answer: D. Silver
• **Silver (Ag)** = Highest electrical conductivity (6.3 × 10⁷ S/m) among all elements. • **Practical limitation** — Copper used instead in cables because silver is expensive and precious. • 💡 Wrong-option analysis: A: Copper is second-best conductor, very cost-effective; B: Aluminium conducts but less efficiently than copper; C: Gold conducts well but too expensive.
Which gas is used for the artificial ripening of green fruits?
Correct Answer: B. Ethylene
• **Ethylene (C₂H₄)** = Plant hormone that regulates ripening, senescence, and stress responses. • **Commercial ripening** — Bananas, mangoes exposed to controlled ethylene in ripening chambers. • 💡 Wrong-option analysis: A: Ethane (C₂H₆) inert, doesn't trigger ripening; C: Acetylene (C₂H₂) toxic to plants; D: Methane doesn't function as plant hormone.
What is the primary constituent of 'LPG' (Liquefied Petroleum Gas)?
Correct Answer: C. Butane
• **Butane (C₄H₁₀)** = Main component of commercial cooking gas, easily liquefied under pressure. • **Storage efficiency** — Liquefies at -0.5°C at 1 atm, enabling safe transport in sealed cylinders. • 💡 Wrong-option analysis: A: Ethane has lower energy density; B: Methane stays gaseous, difficult to liquefy; D: Propane (C₃H₈) is secondary component in LPG mixtures.
Which of the following is an alloy of Copper and Tin?
Correct Answer: B. Bronze
• **Bronze (Cu + Sn)** = Typically 88% copper with 12% tin, harder than pure copper. • **Historical use** — Bronze Age named because this alloy was primary metal for tools and weapons. • 💡 Wrong-option analysis: A: Steel is iron-carbon alloy, not copper; C: Brass is copper-zinc alloy; D: Solder typically lead-tin alloy or lead-free variants.
Which chemical is known as 'Oil of Vitriol'?
Correct Answer: B. Sulfuric acid
• **Sulfuric acid (H₂SO₄)** = Oily appearance and 'vitriol' name from historical production via vitriol minerals. • **King of chemicals** — Essential in fertilizers, batteries, and industrial processes worldwide. • 💡 Wrong-option analysis: A: Acetic acid is sour (vinegar component), not oily; C: Nitric acid is colorless, watery consistency; D: Hydrochloric acid aqueous, gaseous if concentrated.
Which gas is evolved when washing soda is treated with hydrochloric acid?
Correct Answer: C. Carbon dioxide
• **Carbon dioxide** = The reaction between a carbonate and an acid always produces carbon dioxide gas. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: Oxygen; B: Chlorine; D: Hydrogen
What is the common name for 'Calcium Sulfate Hemihydrate'?
Correct Answer: B. Plaster of Paris
• **Plaster of Paris** = Plaster of Paris is formed by heating gypsum to a specific temperature. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: Gypsum; C: Baking soda; D: Bleaching powder
Which non-metal is the only one that exists in liquid state at room temperature?
Correct Answer: B. Bromine
• **Bromine** = Bromine is a reddish-brown liquid with a sharp, choking smell. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: Iodine; C: Mercury; D: Chlorine
Which acid is present in 'Vinegar'?
Correct Answer: A. Acetic acid
• **Acetic acid** = Acetic acid gives vinegar its characteristic sour taste and pungent smell. • (Contextual detail from explanation) • 💡 Wrong-option analysis: B: Tartaric acid; C: Citric acid; D: Lactic acid
Which substance is used to remove the permanent hardness of water?
Correct Answer: D. Washing soda
• **Washing soda** = Washing soda reacts with soluble calcium and magnesium salts to form insoluble precipitates. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: Quick lime; B: Baking soda; C: Bleaching powder