1. The hybridization of the central atom in [Cr(H₂O)₆]³⁺ is –
(A) sp³
(B) d²sp³
(C) sp³d²
(D) dsp²
Answer: (C)
Explanation: Chromium in [Cr(H₂O)₆]³⁺ forms six bonds with water ligands in an octahedral geometry, requiring six hybrid orbitals. Cr³⁺ uses sp³d² hybridization for this arrangement.
2. Which gas is used in the production of sulfuric acid?
(A) Sulfur dioxide
(B) Oxygen
(C) Nitrogen
(D) Both (A) and (B)
Answer: (D)
Explanation: Sulfuric acid (H₂SO₄) is produced via the Contact process, where sulfur dioxide (SO₂) is oxidized with oxygen (O₂) using a vanadium pentoxide catalyst.
3. The bond angle in the CH₄ molecule is –
(A) 90°
(B) 104.5°
(C) 109.5°
(D) 120°
Answer: (C)
Explanation: CH₄ has a tetrahedral shape with four bonding pairs and no lone pairs on carbon, resulting in a bond angle of 109.5°, per VSEPR theory.
4. The primary source of carbon monoxide in the atmosphere is –
(A) Photosynthesis
(B) Incomplete combustion
(C) Volcanic eruptions
(D) Ocean emissions
Answer: (B)
Explanation: Carbon monoxide (CO) is primarily produced by incomplete combustion of fossil fuels in vehicles and industries.
5. Which of the following is a bidentate ligand?
(A) Ammonia
(B) 1,10-Phenanthroline
(C) Chloride
(D) Water
Answer: (B)
Explanation: 1,10-Phenanthroline is a bidentate ligand, binding to a metal ion at two nitrogen atoms, unlike ammonia, chloride, or water, which are monodentate.
6. The half-life of a first-order reaction is –
(A) Proportional to initial concentration
(B) Inversely proportional to initial concentration
(C) Independent of initial concentration
(D) Proportional to temperature
Answer: (C)
Explanation: For a first-order reaction, t₁/₂ = ln(2)/k, which is independent of the initial concentration and depends only on the rate constant (k).
7. The element with the lowest melting point in group 17 is –
(A) Fluorine
(B) Chlorine
(C) Bromine
(D) Iodine
Answer: (A)
Explanation: Melting point increases down group 17 due to stronger London dispersion forces. Fluorine, at the top, has the lowest melting point.
8. The shape of the ICl₄⁻ ion is –
(A) Tetrahedral
(B) Square planar
(C) See-saw
(D) Trigonal bipyramidal
Answer: (B)
Explanation: ICl₄⁻ has four bonding pairs and two lone pairs on iodine, resulting in a square planar shape from an octahedral electron geometry.
9. The catalyst used in the production of methanol from carbon monoxide is –
(A) Zinc oxide and chromium oxide
(B) Platinum
(C) Nickel
(D) Iron
Answer: (A)
Explanation: Methanol (CH₃OH) is produced from CO and H₂ using a mixed catalyst of zinc oxide (ZnO) and chromium oxide (Cr₂O₃) under high pressure.
10. Which of the following ions is diamagnetic?
(A) Mn²⁺
(B) Co²⁺
(C) Zn²⁺
(D) Fe²⁺
Answer: (C)
Explanation: Diamagnetic ions have all paired electrons. Zn²⁺ ([Ar]3d¹⁰) has a fully filled d-subshell, while Mn²⁺, Co²⁺, and Fe²⁺ have unpaired electrons.
11. The functional group in ethers is –
(A) -OH
(B) -O-
(C) -COOH
(D) -CHO
Answer: (B)
Explanation: Ethers are characterized by the -O- group, with an oxygen atom bonded to two alkyl or aryl groups.
12. The pOH of a 0.001 M solution of a strong acid is –
(A) 11
(B) 12
(C) 13
(D) 14
Answer: (A)
Explanation: A strong acid fully dissociates. For 0.001 M acid, [H⁺] = 0.001 M = 10⁻³ M. pH = -log(10⁻³) = 3. pOH = 14 – pH = 14 – 3 = 11.
13. The oxidation state of cobalt in [Co(en)₂Cl₂]⁺ is –
(A) +1
(B) +2
(C) +3
(D) +4
Answer: (C)
Explanation: Ethylenediamine (en) is neutral, Cl⁻ is -1. The complex has a +1 charge. Let Co = x. Then, x + 2(0) + 2(-1) = +1 → x – 2 = +1 → x = +3.
14. Which of the following is a tertiary amine?
(A) CH₃NH₂
(B) (CH₃)₂NH
(C) (CH₃)₃N
(D) C₆H₅NH₂
Answer: (C)
Explanation: A tertiary amine has three alkyl or aryl groups attached to nitrogen. (CH₃)₃N (trimethylamine) is a tertiary amine.
15. The standard Gibbs free energy change (ΔG°) is related to the equilibrium constant by –
(A) ΔG° = RT ln K
(B) ΔG° = -RT ln K
(C) ΔG° = R/T ln K
(D) ΔG° = -R/T ln K
Answer: (B)
Explanation: The relationship is ΔG° = -RT ln K, where a negative ΔG° indicates a spontaneous reaction with K > 1.
16. The metal used in the production of german silver is –
(A) Nickel
(B) Zinc
(C) Copper
(D) All of the above
Answer: (D)
Explanation: German silver is an alloy of copper, nickel, and zinc, used in utensils and decorative items.
17. The monomer of poly(vinyl chloride) is –
(A) Ethylene
(B) Vinyl chloride
(C) Styrene
(D) Tetrafluoroethylene
Answer: (B)
Explanation: Poly(vinyl chloride) (PVC) is a polymer of vinyl chloride (CH₂=CHCl), used in pipes and cables.
18. The rate constant of a second-order reaction has units –
(A) s⁻¹
(B) L mol⁻¹ s⁻¹
(C) mol L⁻¹ s⁻¹
(D) L² mol⁻² s⁻¹
Answer: (B)
Explanation: For a second-order reaction, rate = k[A]², so k has units of L mol⁻¹ s⁻¹ to ensure the rate’s unit is mol L⁻¹ s⁻¹.
19. Which of the following is a basic oxide?
(A) SO₂
(B) CO₂
(C) CaO
(D) P₂O₅
Answer: (C)
Explanation: CaO reacts with water to form Ca(OH)₂, a base, making it a basic oxide. SO₂, CO₂, and P₂O₅ are acidic oxides.
20. The gas used in krypton bulbs is –
(A) Argon
(B) Neon
(C) Krypton
(D) Helium
Answer: (C)
Explanation: Krypton bulbs use krypton gas for improved efficiency and brighter light compared to argon-filled bulbs.
21. The coordination number of Na⁺ in NaCl (rock salt) is –
(A) 4
(B) 6
(C) 8
(D) 12
Answer: (B)
Explanation: In the NaCl (rock salt) structure, each Na⁺ ion is surrounded by six Cl⁻ ions, giving a coordination number of 6.
22. Which of the following is a natural polymer?
(A) Polyethylene
(B) Silk
(C) Nylon
(D) Teflon
Answer: (B)
Explanation: Silk, a protein fiber, is a natural polymer, while polyethylene, nylon, and Teflon are synthetic polymers.
23. The unit of osmotic pressure is –
(A) Pascal
(B) Joule
(C) Newton
(D) Meter
Answer: (A)
Explanation: Osmotic pressure (π = CRT) is a pressure measurement, with SI unit pascal (Pa).
24. The compound responsible for the green color in glass is –
(A) Chromium oxide
(B) Cobalt oxide
(C) Iron oxide
(D) Manganese dioxide
Answer: (A)
Explanation: Chromium oxide (Cr₂O₃) imparts a green color to glass, used in decorative and bottle glass.
25. The number of sigma bonds in benzene (C₆H₆) is –
(A) 6
(B) 9
(C) 12
(D) 15
Answer: (C)
Explanation: Benzene has six C-C single bonds (6 sigma) and six C-H single bonds (6 sigma) in its resonance structure. Total sigma bonds = 6 + 6 = 12.
26. Which of the following is a strong base?
(A) NH₃
(B) CH₃NH₂
(C) KOH
(D) Pyridine
Answer: (C)
Explanation: Potassium hydroxide (KOH) is a strong base, fully dissociating in water, unlike weak bases NH₃, CH₃NH₂, and pyridine.
27. The color of sodium chloride flame in a flame test is –
(A) Yellow
(B) Green
(C) Blue
(D) Red
Answer: (A)
Explanation: Sodium ions produce a yellow flame in a flame test due to electron transitions in the sodium atom.
28. The process of converting a gas to a solid is called –
(A) Sublimation
(B) Deposition
(C) Condensation
(D) Evaporation
Answer: (B)
Explanation: Deposition is the direct transition from gas to solid, such as frost formation.
29. The fourth most abundant metal in Earth’s crust is –
(A) Aluminum
(B) Iron
(C) Calcium
(D) Magnesium
Answer: (D)
Explanation: Magnesium (~2%) is the fourth most abundant metal in Earth’s crust, after aluminum (~8%), iron (~5%), and calcium (~3.6%).
30. The element used in the production of pyrotechnics is –
(A) Barium
(B) Strontium
(C) Aluminum
(D) All of the above
Answer: (D)
Explanation: Barium (green), strontium (red), and aluminum (white sparks) are used in pyrotechnics for their colorful emissions.
31. The functional group in alkyl halides is –
(A) -OH
(B) -X (X = F, Cl, Br, I)
(C) -NH₂
(D) -COOH
Answer: (B)
Explanation: Alkyl halides are characterized by the -X group, where X is a halogen (F, Cl, Br, or I).
32. The rate of diffusion of a gas is inversely proportional to –
(A) Temperature
(B) Square root of molecular weight
(C) Pressure
(D) Volume
Answer: (B)
Explanation: Graham’s law states that the rate of diffusion is inversely proportional to √M, where M is the molecular weight.
33. Which of the following is a sol?
(A) Ink
(B) Milk
(C) Fog
(D) Jelly
Answer: (A)
Explanation: Ink is a sol, a colloid with solid particles dispersed in a liquid. Milk is an emulsion, fog is an aerosol, and jelly is a gel.
34. The oxidation number of nitrogen in NH₄⁺ is –
(A) -3
(B) +3
(C) 0
(D) +1
Answer: (A)
Explanation: In NH₄⁺, H = +1. Let N = x. Then, x + 4(+1) = +1 → x + 4 = +1 → x = -3.
35. The allotrope of carbon used as a lubricant is –
(A) Diamond
(B) Graphite
(C) Fullerene
(D) Charcoal
Answer: (B)
Explanation: Graphite’s layered structure allows sheets to slide, making it an effective lubricant.
36. The SI unit of surface tension is –
(A) N/m
(B) J/m²
(C) N·m
(D) kg/m²
Answer: (A)
Explanation: Surface tension is force per unit length, with SI unit N/m.
37. The compound used as a food preservative is –
(A) Sodium chloride
(B) Potassium sorbate
(C) Ethanol
(D) Chloroform
Answer: (B)
Explanation: Potassium sorbate is used as a food preservative to inhibit mold and yeast growth.
38. The reaction 2Na + Cl₂ → 2NaCl is an example of –
(A) Combination
(B) Decomposition
(C) Displacement
(D) Double displacement
Answer: (A)
Explanation: This is a combination reaction, where sodium and chlorine combine to form sodium chloride.
39. The element with atomic number 17 belongs to –
(A) Alkali metals
(B) Halogens
(C) Noble gases
(D) Chalcogens
Answer: (B)
Explanation: Atomic number 17 corresponds to chlorine, in group 17 (halogens).
40. The vapor pressure of a liquid increases with –
(A) Decreasing temperature
(B) Increasing temperature
(C) Decreasing pressure
(D) Increasing volume
Answer: (B)
Explanation: Vapor pressure increases with temperature, as more molecules gain sufficient energy to enter the gas phase.
41. The compound responsible for the smell of grapes is –
(A) Methyl anthranilate
(B) Ethyl acetate
(C) Ethanol
(D) Acetone
Answer: (A)
Explanation: Methyl anthranilate is an ester responsible for the grape-like odor, used in flavorings.
42. The crystal structure of calcium fluoride (CaF₂) is –
(A) Cubic
(B) Hexagonal
(C) Orthorhombic
(D) Tetragonal
Answer: (A)
Explanation: Calcium fluoride (fluorite) has a cubic crystal structure, with Ca²⁺ and F⁻ ions arranged in a lattice.
43. The gas used in food packaging to extend shelf life is –
(A) Nitrogen
(B) Oxygen
(C) Carbon dioxide
(D) Both (A) and (C)
Answer: (D)
Explanation: Nitrogen and carbon dioxide are used in modified atmosphere packaging to reduce oxidation and microbial growth.
44. The common name for pentanoic acid is –
(A) Caproic acid
(B) Valeric acid
(C) Butyric acid
(D) Propionic acid
Answer: (B)
Explanation: Pentanoic acid (CH₃(CH₂)₃COOH) is commonly known as valeric acid.
45. The phenomenon of settling of colloidal particles under gravity is called –
(A) Tyndall effect
(B) Brownian motion
(C) Sedimentation
(D) Electrophoresis
Answer: (C)
Explanation: Sedimentation is the settling of colloidal particles under gravity, often enhanced by centrifugation.
46. The element used in nuclear reactors as a moderator is –
(A) Carbon
(B) Boron
(C) Graphite
(D) Both (A) and (C)
Answer: (C)
Explanation: Graphite is used as a moderator in nuclear reactors to slow down neutrons, enhancing fission efficiency.
47. The formula of soda ash is –
(A) Na₂CO₃
(B) NaHCO₃
(C) CaCO₃
(D) Na₂SO₄
Answer: (A)
Explanation: Soda ash is sodium carbonate (Na₂CO₃), used in glass and detergent production.
48. The oxidation number of phosphorus in PO₄³⁻ is –
(A) +3
(B) +4
(C) +5
(D) +6
Answer: (C)
Explanation: In PO₄³⁻ (phosphate), O = -2. Let P = x. Then, x + 4(-2) = -3 → x – 8 = -3 → x = +5.
49. Which of the following is a redox reaction?
(A) NaOH + HCl → NaCl + H₂O
(B) Zn + H₂SO₄ → ZnSO₄ + H₂
(C) CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂
(D) NaCl + AgNO₃ → AgCl + NaNO₃
Answer: (B)
Explanation: Zn + H₂SO₄ → ZnSO₄ + H₂ involves a change in oxidation states (Zn: 0 to +2, H: +1 to 0), making it a redox reaction. The others are not.
50. The IUPAC name of CH₃CH₂CH₂COOH is –
(A) Butanoic acid
(B) Propanoic acid
(C) Pentanoic acid
(D) Ethanoic acid
Answer: (A)
Explanation: CH₃CH₂CH₂COOH has four carbon atoms, including the carboxyl group, so its IUPAC name is butanoic acid.