Question 1

Materials (glass types): The inexpensive, common glass used in windows and bottles is called soda glass. Why is it called “soda” glass? Identify the key sodium-containing ingredient used in its manufacture. Choose the correct option.

Accepted Answer

Concept Soda–lime glass is made from silica (SiO₂) + sodium carbonate (Na₂CO₃, “soda”) + calcium carbonate (CaCO₃, “lime”). The sodium carbonate lowers the melting point—hence the name “soda glass.” Final Answer It contains sodium carbonate (“soda”) in its batch

Question 2

Solubility (noble gases): The inert (noble) gases are ____ in water. Choose the correct qualitative description.

Accepted Answer

Concept Noble gases are nonpolar and chemically inert; they are sparingly soluble in water, with solubility increasing modestly with atomic mass due to polarizability. Final Answer Sparingly (very slightly) soluble

Question 3

Concentration units: The number of moles of solute present in 1 kg of solvent is called what? State the correct concentration term and unit basis. Choose the correct option.

Accepted Answer

Concept Molality (m) = moles of solute per kilogram of solvent. (Molarity = moles per liter of solution; mole fraction = ratio of moles; normality = equivalents per liter.) Final Answer Molality

Question 4

Mineral processing (froth flotation): Which oil is commonly used as a frothing agent/collector additive in the froth flotation process? Choose the correct option.

Accepted Answer

Concept In froth flotation, pine oil is widely used as a frother (and sometimes as part of collectors), helping stabilize froth so that hydrophobic mineral particles can be floated off. Final Answer Pine oil

Question 5

Human nutrition (calorific values): The approximate heat energy released when the body metabolizes 1 gram of fat is what? Report the standard physiological energy value. Choose the correct option.

Accepted Answer

Concept Physiological fuel values: carbohydrates ≈ 4 kcal/g, proteins ≈ 4 kcal/g, fats ≈ 9 kcal/g (≈ 37–38 kJ/g). Alcohol ~7 kcal/g. Final Answer 9 kcal (≈ 38 kJ)

Question 6

General science (chemistry): Identify the most abundant noble (rare) gas present in Earth’s atmosphere.  Among the noble gases (He, Ne, Ar, Kr, Xe), which gas occurs in the highest proportion in dry air at sea level? Choose the correct option.

Accepted Answer

Given / Recall Noble (rare) gases in air include He, Ne, Ar, Kr, Xe. Dry air composition by volume: N2 ~78%, O2 ~21%, Ar ~0.93%, CO2 ~0.04%. Concept Among noble gases, the gas with the greatest atmospheric fraction is considered the most abundant. Reasoning Argon is ~0.93% of dry air, far exceeding neon (~18 ppm), helium (~5 ppm), krypton (~1 ppm), xenon (~0.09 ppm). Common pitfalls Confusing overall abundance in the universe (He) with abundance in Earth’s atmosphere (Ar). Final Answer Argon (Ar).

Question 7

Stoichiometry: Calculate the mass of P₄O₁₀ formed from given reactants.  Reaction: P₄ + 5O₂ → P₄O₁₀ Given 1.33 g of P₄ and 5.07 g of O₂ react completely under standard conditions. Find the mass of P₄O₁₀ produced (assume complete reaction and pure re…

Accepted Answer

Given Reaction: P4 + 5O2 → P4O10 m(P4) = 1.33 g; M(P4) = 4×31 = 124 g/mol m(O2) = 5.07 g; M(O2) = 32 g/mol M(P4O10) = 4×31 + 10×16 = 124 + 160 = 284 g/mol Approach Find the limiting reagent, then compute product moles and mass. Step-by-step n(P4) = 1.33/124 = 0.010726 moln(O2) = 5.07/32 = 0.15844 molO2 needed = 5×0.010726 = 0.05363 mol (available 0.15844 mol → excess)P4 is limiting, so n(P4O10) = n(P4) = 0.010726 molm(P4O10) = 0.010726 × 284 = 3.046 g Verification Significant figures from 1.33 and 5.07 → ~3.05 g. Final Answer 3.046 g (≈ 3.05 g).

Question 8

General metallurgy: Identify the most malleable metal among common metals.  Malleability refers to the ability of a metal to be hammered into thin sheets without breaking. Choose the correct metal.

Accepted Answer

Concept Malleability = ability to be hammered/rolled into sheets. Gold > Silver > Aluminium ≈ Copper ≫ Iron for malleability. Reasoning Gold can be beaten into extremely thin leaf (∼0.1 µm), making it the most malleable common metal. Final Answer Gold.

Question 9

Gas solubility law: Name the law relating dissolved gas to its partial pressure.  Statement focus: The quantity of a gas dissolved in a liquid is directly proportional to the gas’s partial pressure above the liquid at constant temperature. Choose th…

Accepted Answer

Concept At constant temperature, gas solubility S in a liquid: S = kH·P (partial pressure). This is Henry’s law. Pitfalls Do not confuse with Boyle’s (P–V), Charles’s (V–T), or Raoult’s (solution vapor pressure) laws. Final Answer Henry’s law.

Question 10

Indian geography (minerals): Identify India’s most extensive commercially valuable monazite (thorium) sand deposits.  Focus on coastal placer deposits known for thorium-bearing monazite sands. Choose the correct location.

Accepted Answer

Given/Context Monazite sands rich in thorium occur in beach placers. Reasoning India’s best-known extensive monazite placers are along the Kerala coast (e.g., near Kollam/Quilon and Aluva), with additional significant pockets in Tamil Nadu and Odisha. The most extensive, commercially valuable deposits are classically associated with Kerala’s Travancore–Malabar belt. Final Answer Kerala coast (Travancore–Malabar belt).

Question 11

Materials chemistry: Identify the main chemical constituent of common clay minerals.  Clay (e.g., kaolinite) is composed primarily of alumino-silicates with water of crystallization. Choose the most appropriate constituent.

Accepted Answer

Concept Common clays such as kaolinite have composition approximated by Al2O3·2SiO2·2H2O (hydrated aluminium silicate). Final Answer Hydrated aluminium silicate.

Question 12

Metallurgy process identification: Name the process where metal is obtained in a fused (molten) state.  Context: Extraction step that yields molten metal from its ore or intermediate. Choose the correct term.

Accepted Answer

Definitions Calcination: heating in absence of air to remove volatiles. Roasting: heating in presence of O2 to convert sulfides/impurities. Smelting: extraction of metal in molten/fused state, often with reducing agents/flux. Final Answer Smelting.

Question 13

Thermal property: Name the quantity defined as heat required to raise a body’s temperature by 1 K.  Distinguish between per-body and per-unit-mass definitions. Choose the correct physical quantity.

Accepted Answer

Concept Heat capacity (C) is the heat required to raise the temperature of an object by 1 K. Specific heat capacity (c) is per unit mass. Final Answer Heat capacity.

Question 14

Materials purification: Zone refining is typically used to purify which type of materials?  Focus: Ultra-high purity for electronic/semiconductor applications. Choose the best example.

Accepted Answer

Concept Zone refining moves a molten zone along a rod; impurities concentrate in the melt and are swept to one end. It is used for semiconductors like Ge and Si. Final Answer Germanium (Ge) for semiconductors.

Question 15

Organic acids (etymology): Why is methanoic acid called “formic acid”?  Formic acid name origin relates to a Latin word linked to insects. Choose the correct reason.

Accepted Answer

Concept/History Formic comes from Latin formica = ant. Early chemists obtained methanoic (formic) acid by distilling crushed ants. Final Answer It was first isolated by distilling ants (Latin: 'formica').

Question 16

Identify the compound: The structure C₆H₅–CO–CH₃ corresponds to which named aromatic ketone?  Recognize common IUPAC/trivial names used in introductory organic chemistry. Choose the correct name.

Accepted Answer

Reasoning C6H5–CO–CH3 is an aromatic ketone with acyl = benzoyl and alkyl = methyl. Common name: Acetophenone (IUPAC: 1-phenylethan-1-one). Benzaldehyde is C6H5–CHO; benzophenone is C6H5–CO–C6H5; toluene is C6H5–CH3. Final Answer Acetophenone.

Question 17

Nuclear basics: What does the mass number of a nucleus represent?  Interpret the definition in terms of subatomic particles inside the nucleus. Choose the correct description.

Accepted Answer

Concept Mass number A = Z (protons) + N (neutrons). Electrons are not counted in A. Final Answer Total number of nucleons (protons + neutrons).

Question 18

Isomer count: Determine the maximum number of isomers for the alkene C₄H₈.  Consider positional and geometrical (cis–trans) isomerism where applicable. Choose the correct count.

Accepted Answer

Approach Structural isomers: 1-butene, 2-butene, 2-methylpropene. 2-Butene exhibits geometric isomerism: cis-2-butene and trans-2-butene. Count 1-butene (1), cis-2-butene (2), trans-2-butene (3), 2-methylpropene (4) ⇒ total = 4. Final Answer 4.

Question 19

Radioactivity decay: An isotope has a half-life of 2 hours. What fraction remains after 6 hours?  Assume simple first-order decay. Choose the correct remaining fraction.

Accepted Answer

Given Half-life t1/2 = 2 h; elapsed time t = 6 h. Calculation Number of half-lives = t / t1/2 = 6/2 = 3.Remaining fraction = (1/2)3 = 1/8 = 0.125. Final Answer 1/8 of the initial quantity remains.

Question 20

Metals from seawater: Identify the metal commonly extracted from seawater.  Focus on large-scale recovery from seawater/brine. Choose the correct metal.

Accepted Answer

Concept Seawater/brines are significant sources of magnesium (as MgCl2), later reduced or electrolyzed to Mg metal; NaCl is mainly for salt/chemical feedstock, not metal extraction directly from seawater. Final Answer Magnesium.

Chemistry Questions