1. The hybridization of the central atom in XeF₄ is –
(A) sp³
(B) sp³d
(C) sp³d²
(D) dsp²
Answer: (C)
Explanation: Xenon in XeF₄ forms four bonds with fluorine and has two lone pairs, requiring six hybrid orbitals. This is achieved through sp³d² hybridization, resulting in a square planar shape per VSEPR theory.
2. Which gas is used in the production of sulfuric acid?
(A) Sulfur dioxide
(B) Nitrogen
(C) Oxygen
(D) Carbon dioxide
Answer: (A)
Explanation: Sulfur dioxide (SO₂) is oxidized to sulfur trioxide (SO₃) in the Contact process, which is then hydrated to produce sulfuric acid (H₂SO₄).
3. The bond angle in the O₃ (ozone) molecule is approximately –
(A) 90°
(B) 109.5°
(C) 117°
(D) 120°
Answer: (C)
Explanation: Ozone has a bent shape with two bonding pairs and one lone pair on the central oxygen, leading to a bond angle of ~117° due to lone pair repulsion, per VSEPR theory.
4. The primary source of ammonia in the atmosphere is –
(A) Volcanic activity
(B) Agricultural activities
(C) Combustion of fossil fuels
(D) Industrial emissions
Answer: (B)
Explanation: Ammonia (NH₃) is primarily released from agricultural activities, such as fertilizer use and livestock waste, contributing to atmospheric nitrogen cycles.
5. Which of the following is a tridentate ligand?
(A) Ethylenediamine
(B) Diethylenetriamine
(C) Cyanide
(D) Ammonia
Answer: (B)
Explanation: A tridentate ligand binds to a metal ion at three sites. Diethylenetriamine (H₂NCH₂CH₂NHCH₂CH₂NH₂) has three nitrogen atoms for coordination, unlike the others.
6. The half-life of a first-order reaction is independent of –
(A) Rate constant
(B) Initial concentration
(C) Temperature
(D) Activation energy
Answer: (B)
Explanation: For a first-order reaction, t₁/₂ = ln(2)/k, which depends on the rate constant (k) but is independent of the initial concentration of the reactant.
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 van der Waals forces. Fluorine, at the top, has the lowest melting point.
8. The shape of the SF₆ molecule is –
(A) Tetrahedral
(B) Trigonal bipyramidal
(C) Octahedral
(D) Square planar
Answer: (C)
Explanation: SF₆ has six bonding pairs and no lone pairs around sulfur, resulting in an octahedral shape with 90° bond angles.
9. The catalyst used in the Haber process for ammonia synthesis is –
(A) Iron
(B) Platinum
(C) Nickel
(D) Copper
Answer: (A)
Explanation: The Haber process (N₂ + 3H₂ → 2NH₃) uses iron with promoters like Al₂O₃ to catalyze the reaction under high pressure and temperature.
10. Which of the following ions is paramagnetic?
(A) Ag⁺
(B) Cu²⁺
(C) Zn²⁺
(D) Cd²⁺
Answer: (B)
Explanation: Paramagnetic ions have unpaired electrons. Cu²⁺ ([Ar]3d⁹) has one unpaired electron, while Ag⁺, Zn²⁺, and Cd²⁺ have fully paired orbitals.
11. The functional group in alkyl halides is –
(A) -OH
(B) -X (where X is a halogen)
(C) -NH₂
(D) -CHO
Answer: (B)
Explanation: Alkyl halides are characterized by a carbon-halogen bond (-X, where X is F, Cl, Br, or I).
12. The pH of a 0.001 M solution of a strong base is –
(A) 10
(B) 11
(C) 12
(D) 13
Answer: (B)
Explanation: A strong base fully dissociates. For 0.001 M base, [OH⁻] = 0.001 M = 10⁻³ M. pOH = -log(10⁻³) = 3. pH = 14 – pOH = 14 – 3 = 11.
13. The oxidation state of manganese in MnO₂ is –
(A) +2
(B) +3
(C) +4
(D) +7
Answer: (C)
Explanation: In MnO₂, O = -2. Let Mn = x. Then, x + 2(-2) = 0 → x – 4 = 0 → x = +4.
14. Which of the following is a secondary halide?
(A) CH₃CH₂Cl
(B) (CH₃)₂CHCl
(C) (CH₃)₃CCl
(D) CH₂=CHCl
Answer: (B)
Explanation: A secondary halide has the halogen on a carbon bonded to two other carbons. (CH₃)₂CHCl (isopropyl chloride) is a secondary halide.
15. The standard Gibbs free energy of formation is defined at –
(A) 0 K
(B) 273 K
(C) 298 K
(D) 373 K
Answer: (C)
Explanation: The standard Gibbs free energy of formation (ΔG_f°) is defined for compounds formed from their elements in standard states at 298 K and 1 atm.
16. The metal used in the production of galvanized iron is –
(A) Zinc
(B) Copper
(C) Aluminum
(D) Tin
Answer: (A)
Explanation: Galvanized iron is coated with zinc to prevent corrosion through sacrificial protection.
17. The monomer of PVC is –
(A) Ethylene
(B) Vinyl chloride
(C) Styrene
(D) Tetrafluoroethylene
Answer: (B)
Explanation: Polyvinyl chloride (PVC) is a polymer of vinyl chloride (CH₂=CHCl), used in pipes and cables.
18. The rate constant of a zero-order reaction has the unit –
(A) s⁻¹
(B) mol L⁻¹ s⁻¹
(C) L mol⁻¹ s⁻¹
(D) mol⁻¹ L s⁻¹
Answer: (B)
Explanation: For a zero-order reaction, rate = k, so k has units of mol L⁻¹ s⁻¹ to match the rate’s unit.
19. Which of the following is a basic oxide?
(A) CO₂
(B) SO₃
(C) K₂O
(D) P₂O₅
Answer: (C)
Explanation: K₂O reacts with water to form KOH, a strong base, making it a basic oxide. CO₂, SO₃, and P₂O₅ are acidic oxides.
20. The gas used in neon signs is –
(A) Helium
(B) Neon
(C) Argon
(D) Krypton
Answer: (B)
Explanation: Neon gas is used in neon signs, producing a bright red-orange glow when electrified.
21. The coordination number of Na⁺ in NaCl crystal 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 synthetic polymer?
(A) Cellulose
(B) Starch
(C) Polystyrene
(D) Proteins
Answer: (C)
Explanation: Polystyrene is a synthetic polymer, while cellulose, starch, and proteins are natural polymers.
23. The unit of specific heat capacity is –
(A) J/kg·K
(B) J/mol·K
(C) J/m³·K
(D) J/kg
Answer: (A)
Explanation: Specific heat capacity is the heat required to raise 1 kg of a substance by 1 K, with SI unit J/kg·K.
24. The compound responsible for the green color in glass is –
(A) Iron(II) oxide
(B) Chromium(III) oxide
(C) Copper oxide
(D) Manganese dioxide
Answer: (B)
Explanation: Chromium(III) oxide (Cr₂O₃) imparts a green color to glass, used in decorative glassware.
25. The number of pi bonds in ethene (C₂H₄) is –
(A) 1
(B) 2
(C) 3
(D) 4
Answer: (A)
Explanation: Ethene (H₂C=CH₂) has one double bond, consisting of one sigma and one pi bond, so the number of pi bonds is 1.
26. Which of the following is a weak acid?
(A) H₂SO₄
(B) HNO₃
(C) H₃PO₄
(D) HCl
Answer: (C)
Explanation: Phosphoric acid (H₃PO₄) is a weak acid, partially dissociating in water, unlike strong acids H₂SO₄, HNO₃, and HCl.
27. The color of sodium chloride flame in a flame test is –
(A) Green
(B) Yellow
(C) Blue
(D) Red
Answer: (B)
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 liquid to a gas below its boiling point is –
(A) Sublimation
(B) Evaporation
(C) Condensation
(D) Deposition
Answer: (B)
Explanation: Evaporation is the process where liquid molecules escape into the gas phase at the surface, below the boiling point.
29. The third most abundant element in Earth’s crust is –
(A) Oxygen
(B) Silicon
(C) Aluminum
(D) Iron
Answer: (C)
Explanation: Aluminum (~8%) is the third most abundant element in Earth’s crust, after oxygen (~46%) and silicon (~27%).
30. The element used in the production of fireworks is –
(A) Strontium
(B) Barium
(C) Magnesium
(D) All of the above
Answer: (D)
Explanation: Strontium (red), barium (green), and magnesium (white) are used in fireworks to produce colored flames.
31. The functional group in ethers is –
(A) -OH
(B) -O-
(C) -CHO
(D) -COOH
Answer: (B)
Explanation: Ethers are characterized by an oxygen atom bonded to two alkyl or aryl groups (-O-).
32. The rate of effusion of a gas is inversely proportional to –
(A) Temperature
(B) Pressure
(C) Square root of molecular weight
(D) Volume
Answer: (C)
Explanation: Graham’s law states that the rate of effusion is inversely proportional to √M, where M is the molecular weight.
33. Which of the following is an aerosol?
(A) Milk
(B) Fog
(C) Jelly
(D) Sugar syrup
Answer: (B)
Explanation: Fog is an aerosol, a colloid with liquid droplets dispersed in a gas. Milk is an emulsion, jelly is a gel, and sugar syrup is a solution.
34. The oxidation number of sulfur in H₂S is –
(A) -2
(B) +2
(C) +4
(D) +6
Answer: (A)
Explanation: In H₂S, H = +1. Let S = x. Then, 2(+1) + x = 0 → 2 + x = 0 → x = -2.
35. The allotrope of carbon used in lubricants is –
(A) Diamond
(B) Graphite
(C) Fullerene
(D) Charcoal
Answer: (B)
Explanation: Graphite’s layered structure allows layers to slide over each other, making it an effective lubricant.
36. The SI unit of osmotic pressure is –
(A) Pascal
(B) Bar
(C) Atm
(D) Torr
Answer: (A)
Explanation: Osmotic pressure is a pressure measurement, with SI unit pascal (Pa).
37. The compound used as an insecticide is –
(A) DDT
(B) Ethanol
(C) Sodium chloride
(D) Formaldehyde
Answer: (A)
Explanation: DDT (dichlorodiphenyltrichloroethane) was historically used as an insecticide, though its use is now restricted due to environmental concerns.
38. The reaction 2Na + 2H₂O → 2NaOH + H₂ is an example of –
(A) Combination
(B) Decomposition
(C) Displacement
(D) Double displacement
Answer: (C)
Explanation: This is a displacement reaction, where sodium displaces hydrogen from water due to its higher reactivity.
39. The element with atomic number 17 belongs to –
(A) Alkali metals
(B) Halogens
(C) Noble gases
(D) Alkaline earth metals
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) Increasing volume
(D) Decreasing pressure
Answer: (B)
Explanation: Vapor pressure increases with temperature, as more molecules gain energy to escape into the gas phase.
41. The compound responsible for the smell of paint is –
(A) Acetone
(B) Ethanol
(C) Toluene
(D) Formaldehyde
Answer: (C)
Explanation: Toluene, a volatile organic compound, contributes to the characteristic smell of paints and solvents.
42. The crystal structure of calcium fluoride (CaF₂) is –
(A) Body-centered cubic
(B) Face-centered cubic
(C) Hexagonal
(D) Orthorhombic
Answer: (B)
Explanation: CaF₂ has a fluorite structure, which is a type of face-centered cubic arrangement.
43. The gas used in laser printers is –
(A) Helium
(B) Neon
(C) Argon
(D) Krypton
Answer: (A)
Explanation: Helium is used in laser printers to cool laser components and maintain stable operation.
44. The common name for pentanedioic acid is –
(A) Malonic acid
(B) Succinic acid
(C) Glutaric acid
(D) Oxalic acid
Answer: (C)
Explanation: Pentanedioic acid (HOOC-(CH₂)₃-COOH) is commonly known as glutaric acid.
45. The phenomenon of settling of colloidal particles is called –
(A) Tyndall effect
(B) Brownian motion
(C) Electrophoresis
(D) Coagulation
Answer: (D)
Explanation: Coagulation is the process where colloidal particles aggregate and settle, often induced by adding electrolytes.
46. The element used in cathode ray tubes is –
(A) Tungsten
(B) Mercury
(C) Barium
(D) Cesium
Answer: (C)
Explanation: Barium is used in cathode ray tubes to coat the cathode, enhancing electron emission.
47. The formula of bleaching powder is –
(A) CaCl₂
(B) Ca(OCl)Cl
(C) Ca(OH)₂
(D) CaSO₄
Answer: (B)
Explanation: Bleaching powder is calcium hypochlorite chloride (Ca(OCl)Cl), used as a disinfectant and bleaching agent.
48. The oxidation number of phosphorus in H₃PO₃ is –
(A) +3
(B) +4
(C) +5
(D) +2
Answer: (A)
Explanation: In H₃PO₃, H = +1, O = -2. Let P = x. Then, 3(+1) + x + 3(-2) = 0 → 3 + x – 6 = 0 → x = +3.
49. Which of the following is a conjugate base?
(A) H₃O⁺
(B) NH₄⁺
(C) HCO₃⁻
(D) H₂SO₄
Answer: (C)
Explanation: A conjugate base is formed by losing a proton. HCO₃⁻ is the conjugate base of H₂CO₃, unlike the others, which are acids or cations.
50. The IUPAC name of CH₃CH(OH)CH₃ is –
(A) Propan-1-ol
(B) Propan-2-ol
(C) Ethanol
(D) Butan-1-ol
Answer: (B)
Explanation: CH₃CH(OH)CH₃ has three carbon atoms with a hydroxyl group on the second carbon, so its IUPAC name is propan-2-ol.