1. The hybridization of the central atom in BrF₅ is –
(A) sp³
(B) sp³d
(C) sp³d²
(D) dsp²
Answer: (C)
Explanation: Bromine in BrF₅ forms five bonds with fluorine and has one lone pair, requiring six hybrid orbitals. This is achieved through sp³d² hybridization, resulting in a square pyramidal shape per VSEPR theory.
2. Which gas is used in the production of bleaching powder?
(A) Chlorine
(B) Oxygen
(C) Nitrogen
(D) Carbon dioxide
Answer: (A)
Explanation: Bleaching powder (Ca(OCl)Cl) is produced by passing chlorine gas over dry slaked lime (Ca(OH)₂) in the chlorination process.
3. The bond angle in the BF₃ molecule is –
(A) 90°
(B) 109.5°
(C) 120°
(D) 180°
Answer: (C)
Explanation: BF₃ has a trigonal planar shape with three bonding pairs and no lone pairs on boron, resulting in a bond angle of 120° per VSEPR theory.
4. The primary source of methane in the atmosphere is –
(A) Volcanic activity
(B) Wetlands
(C) Industrial emissions
(D) Combustion
Answer: (B)
Explanation: Methane (CH₄) is primarily produced by anaerobic bacteria in wetlands, rice paddies, and livestock digestion, contributing significantly to greenhouse gases.
5. Which of the following is a monodentate ligand?
(A) Ethylenediamine
(B) Oxalate
(C) Cyanide
(D) Acetylacetonate
Answer: (C)
Explanation: A monodentate ligand binds to a metal ion at one site. Cyanide (CN⁻) binds via its carbon atom, while ethylenediamine, oxalate, and acetylacetonate are bidentate.
6. The rate of a zero-order reaction is –
(A) Proportional to [Reactant]
(B) Independent of [Reactant]
(C) Proportional to [Reactant]²
(D) Inversely proportional to [Reactant]
Answer: (B)
Explanation: For a zero-order reaction, the rate law is rate = k, meaning the rate is constant and independent of reactant concentration.
7. The element with the lowest ionization energy in group 14 is –
(A) Carbon
(B) Silicon
(C) Tin
(D) Lead
Answer: (D)
Explanation: Ionization energy decreases down a group due to increasing atomic size. Lead, at the bottom of group 14, has the lowest ionization energy.
8. The shape of the PCl₃ molecule is –
(A) Trigonal planar
(B) Tetrahedral
(C) Trigonal pyramidal
(D) Linear
Answer: (C)
Explanation: PCl₃ has three bonding pairs and one lone pair on phosphorus, resulting in a trigonal pyramidal shape with bond angles of ~107°.
9. The catalyst used in the production of polythene is –
(A) Ziegler-Natta catalyst
(B) Platinum
(C) Nickel
(D) Vanadium pentoxide
Answer: (A)
Explanation: The Ziegler-Natta catalyst (titanium-based) is used in the polymerization of ethylene to produce polythene (polyethylene).
10. Which of the following ions is paramagnetic?
(A) Cu⁺
(B) Zn²⁺
(C) Fe³⁺
(D) Ca²⁺
Answer: (C)
Explanation: Paramagnetic ions have unpaired electrons. Fe³⁺ ([Ar]3d⁵) has five unpaired electrons, while Cu⁺, Zn²⁺, and Ca²⁺ have fully paired or empty orbitals.
11. The functional group in ketones is –
(A) -CHO
(B) -COOH
(C) -CO-
(D) -OH
Answer: (C)
Explanation: Ketones are characterized by the carbonyl group (-CO-), with the carbon bonded to two alkyl groups.
12. The pH of a 0.01 M solution of a strong acid is –
(A) 1
(B) 2
(C) 3
(D) 4
Answer: (B)
Explanation: A strong acid fully dissociates. For 0.01 M acid, [H⁺] = 0.01 M = 10⁻² M. pH = -log(10⁻²) = 2.
13. The oxidation state of cobalt in [Co(NH₃)₆]³⁺ is –
(A) +2
(B) +3
(C) +4
(D) +6
Answer: (B)
Explanation: NH₃ is a neutral ligand. The complex has a +3 charge, so cobalt’s oxidation state is +3 to balance the charge.
14. Which of the following is a tertiary amine?
(A) CH₃NH₂
(B) (CH₃)₂NH
(C) (CH₃)₃N
(D) NH₃
Answer: (C)
Explanation: A tertiary amine has three alkyl groups attached to nitrogen. (CH₃)₃N (trimethylamine) is a tertiary amine.
15. The enthalpy change of a reaction is equal to –
(A) Work done
(B) Heat absorbed or released at constant pressure
(C) Entropy change
(D) Free energy change
Answer: (B)
Explanation: Enthalpy change (ΔH) represents the heat absorbed or released by a system at constant pressure, per the first law of thermodynamics.
16. The metal used in the production of brass is –
(A) Iron
(B) Zinc
(C) Aluminum
(D) Tin
Answer: (B)
Explanation: Brass is an alloy of copper and zinc, valued for its corrosion resistance and malleability.
17. The monomer of nylon-6,6 is –
(A) Adipic acid and hexamethylenediamine
(B) Caprolactam
(C) Ethylene
(D) Styrene
Answer: (A)
Explanation: Nylon-6,6 is a polyamide formed by the condensation of adipic acid and hexamethylenediamine.
18. The rate constant of a first-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: (A)
Explanation: For a first-order reaction, rate = k[A], so k has units of s⁻¹ to ensure the rate’s unit is mol L⁻¹ s⁻¹.
19. Which of the following is a neutral salt?
(A) NH₄Cl
(B) Na₂CO₃
(C) NaCl
(D) NaHCO₃
Answer: (C)
Explanation: NaCl, formed from a strong acid (HCl) and a strong base (NaOH), is a neutral salt, producing neither H⁺ nor OH⁻ in solution.
20. The gas used in high-intensity discharge lamps is –
(A) Neon
(B) Argon
(C) Xenon
(D) Helium
Answer: (C)
Explanation: Xenon is used in high-intensity discharge lamps (e.g., car headlights) due to its bright white light when electrified.
21. The coordination number of Cu²⁺ in CuSO₄·5H₂O is –
(A) 4
(B) 6
(C) 8
(D) 12
Answer: (B)
Explanation: In CuSO₄·5H₂O, Cu²⁺ is coordinated by six water molecules in an octahedral arrangement, giving a coordination number of 6.
22. Which of the following is a synthetic rubber?
(A) Starch
(B) Neoprene
(C) Cellulose
(D) Natural rubber
Answer: (B)
Explanation: Neoprene is a synthetic rubber (polychloroprene), while starch and cellulose are natural polymers, and natural rubber is derived from latex.
23. The unit of equivalent conductance is –
(A) S·m²/equiv
(B) S/m
(C) Ohm·m
(D) S·m²/mol
Answer: (A)
Explanation: Equivalent conductance (Λeq) is specific conductance divided by equivalent concentration, with SI unit S·m²/equiv.
24. The compound responsible for the blue color in fireworks is –
(A) Copper chloride
(B) Strontium nitrate
(C) Barium chloride
(D) Sodium chloride
Answer: (A)
Explanation: Copper chloride produces a blue flame in fireworks due to the emission spectrum of copper ions.
25. The number of pi bonds in benzene (C₆H₆) is –
(A) 3
(B) 4
(C) 5
(D) 6
Answer: (A)
Explanation: Benzene has three alternating double bonds, each with one pi bond, for a total of three pi bonds.
26. Which of the following is a weak base?
(A) NaOH
(B) KOH
(C) NH₃
(D) Ca(OH)₂
Answer: (C)
Explanation: Ammonia (NH₃) is a weak base, partially dissociating in water, unlike strong bases NaOH, KOH, and Ca(OH)₂.
27. The color of iodine solid is –
(A) Yellow
(B) Black with metallic luster
(C) Green
(D) Red
Answer: (B)
Explanation: Solid iodine (I₂) appears black with a metallic luster due to its molecular structure and electronic properties.
28. The process of converting a solid to a liquid is called –
(A) Sublimation
(B) Melting
(C) Evaporation
(D) Condensation
Answer: (B)
Explanation: Melting is the phase transition from solid to liquid, such as ice to water.
29. The second most abundant metal in Earth’s crust is –
(A) Aluminum
(B) Iron
(C) Calcium
(D) Magnesium
Answer: (B)
Explanation: Iron is the second most abundant metal in Earth’s crust (~5%), after aluminum (~8%).
30. The element used in matches is –
(A) Sulfur
(B) Phosphorus
(C) Potassium chlorate
(D) All of the above
Answer: (D)
Explanation: Matches use red phosphorus (on the striking surface), sulfur, and potassium chlorate (in the match head) for ignition.
31. The functional group in esters is –
(A) -CHO
(B) -COOH
(C) -COOR
(D) -OH
Answer: (C)
Explanation: Esters are characterized by the -COOR group, with a carbonyl bonded to an alkoxy group.
32. The rate of effusion of a gas is proportional to –
(A) Molecular weight
(B) Inverse of square root of molecular weight
(C) Temperature only
(D) Pressure only
Answer: (B)
Explanation: Graham’s law states that the rate of effusion is proportional to 1/√M, where M is the molecular weight.
33. Which of the following is a foam?
(A) Milk
(B) Whipped cream
(C) Sugar syrup
(D) Vinegar
Answer: (B)
Explanation: Whipped cream is a foam, a colloid with gas bubbles dispersed in a liquid. Milk is an emulsion, while sugar syrup and vinegar are solutions.
34. The oxidation number of nitrogen in NH₄⁺ is –
(A) -3
(B) +3
(C) +5
(D) 0
Answer: (A)
Explanation: In NH₄⁺, H = +1. Let N = x. Then, x + 4(+1) = +1 → x + 4 = 1 → x = -3.
35. The allotrope of phosphorus used in matches is –
(A) White phosphorus
(B) Red phosphorus
(C) Black phosphorus
(D) Violet phosphorus
Answer: (B)
Explanation: Red phosphorus, less reactive than white phosphorus, is used on matchbox striking surfaces for safety.
36. The SI unit of molality is –
(A) mol/kg
(B) mol/L
(C) kg/mol
(D) mol/m³
Answer: (A)
Explanation: Molality is moles of solute per kilogram of solvent, with SI unit mol/kg.
37. The compound used as a food additive is –
(A) Sodium chloride
(B) Sodium benzoate
(C) Ethanol
(D) All of the above
Answer: (D)
Explanation: Sodium chloride (salt), sodium benzoate (preservative), and ethanol (in some beverages) are used as food additives.
38. The reaction 2KClO₃ → 2KCl + 3O₂ is an example of –
(A) Combination
(B) Decomposition
(C) Displacement
(D) Double displacement
Answer: (B)
Explanation: This is a decomposition reaction, where potassium chlorate breaks down into potassium chloride and oxygen upon heating.
39. The element with atomic number 11 belongs to –
(A) Alkali metals
(B) Halogens
(C) Noble gases
(D) Alkaline earth metals
Answer: (A)
Explanation: Atomic number 11 corresponds to sodium, in group 1 (alkali metals).
40. The boiling point of a liquid increases with –
(A) Decreasing pressure
(B) Increasing pressure
(C) Decreasing temperature
(D) Increasing volume
Answer: (B)
Explanation: The boiling point of a liquid increases with increasing pressure, as higher pressure requires more energy to overcome intermolecular forces.
41. The compound responsible for the smell of vinegar is –滨
System: Acetic acid
(A) Formic acid
(B) Acetic acid
(C) Propionic acid
(D) Butyric acid
Answer: (B)
Explanation: The characteristic smell of vinegar is due to acetic acid (CH₃COOH), a weak organic acid present in concentrations of 4–8% in vinegar.
42. The crystal structure of diamond is –
(A) Hexagonal
(B) Face-centered cubic
(C) Tetrahedral
(D) Body-centered cubic
Answer: (C)
Explanation: Diamond has a tetrahedral crystal structure, with each carbon atom covalently bonded to four others in a three-dimensional network.
43. The gas used in sodium-vapor lamps is –
(A) Neon
(B) Argon
(C) Sodium vapor
(D) Mercury vapor
Answer: (C)
Explanation: Sodium-vapor lamps use sodium vapor, which emits a characteristic yellow light when electrified.
44. The common name for propanedioic acid is –
(A) Malonic acid
(B) Oxalic acid
(C) Succinic acid
(D) Glutaric acid
Answer: (A)
Explanation: Propanedioic acid (HOOC-CH₂-COOH) is commonly known as malonic acid, used in organic synthesis.
45. The phenomenon of random movement of colloidal particles is called –
(A) Tyndall effect
(B) Brownian motion
(C) Electrophoresis
(D) Coagulation
Answer: (B)
Explanation: Brownian motion is the random movement of colloidal particles due to collisions with solvent molecules.
46. The element used in thermometers is –
(A) Mercury
(B) Gallium
(C) Cesium
(D) Sodium
Answer: (A)
Explanation: Mercury was traditionally used in thermometers due to its liquid state and thermal expansion properties, though safer alternatives like alcohol are now common.
47. The formula of hydrated lime is –
(A) CaCO₃
(B) CaO
(C) Ca(OH)₂
(D) CaSO₄·2H₂O
Answer: (C)
Explanation: Hydrated lime, also known as slaked lime, is calcium hydroxide (Ca(OH)₂), used in construction and agriculture.
48. The oxidation number of phosphorus in PO₄³⁻ is –
(A) +3
(B) +4
(C) +5
(D) +6
Answer: (C)
Explanation: In PO₄³⁻, O = -2. Let P = x. Then, x + 4(-2) = -3 → x – 8 = -3 → x = +5.
49. Which of the following is a buffer solution?
(A) NaCl + H₂O
(B) HNO₃ + NaNO₃
(C) H₃PO₄ + NaH₂PO₄
(D) HCl + NaOH
Answer: (C)
Explanation: A buffer solution resists pH changes and consists of a weak acid and its conjugate base. H₃PO₄ (weak acid) and NaH₂PO₄ (its conjugate base) form a buffer.
50. The IUPAC name of CH₃CH₂COOH is –
(A) Methanoic acid
(B) Ethanoic acid
(C) Propanoic acid
(D) Butanoic acid
Answer: (C)
Explanation: CH₃CH₂COOH has three carbon atoms and a carboxylic acid group, so its IUPAC name is propanoic acid.