1. The hybridization of the central atom in [Cu(NH₃)₄]²⁺ is –
(A) sp³
(B) dsp²
(C) sp³d
(D) d²sp³
Answer: (B)
Explanation: Copper in [Cu(NH₃)₄]²⁺ forms four bonds with ammonia ligands in a square planar geometry, requiring four hybrid orbitals. Cu²⁺ uses dsp² hybridization for this arrangement.
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 (Cl₂) over dry slaked lime (Ca(OH)₂).
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 chlorofluorocarbons (CFCs) in the atmosphere is –
(A) Volcanic eruptions
(B) Industrial refrigerants
(C) Agricultural activities
(D) Combustion
Answer: (B)
Explanation: CFCs, which deplete the ozone layer, were primarily released from industrial refrigerants, aerosols, and foam production before their phase-out.
5. Which of the following is a tridentate ligand?
(A) Ammonia
(B) Terpyridine
(C) Cyanide
(D) Oxalate
Answer: (B)
Explanation: Terpyridine is a tridentate ligand, binding to a metal ion at three nitrogen atoms, unlike ammonia and cyanide (monodentate) or oxalate (bidentate).
6. The Le Chatelier’s principle applies to –
(A) Rate of reaction
(B) Equilibrium systems
(C) Catalyst activity
(D) Activation energy
Answer: (B)
Explanation: Le Chatelier’s principle predicts how a system at equilibrium responds to changes in concentration, pressure, or temperature to re-establish equilibrium.
7. The element with the highest electronegativity in group 15 is –
(A) Nitrogen
(B) Phosphorus
(C) Arsenic
(D) Antimony
Answer: (A)
Explanation: Electronegativity decreases down a group due to increasing atomic size. Nitrogen, at the top of group 15, has the highest electronegativity.
8. The shape of the XeF₆ molecule is –
(A) Octahedral
(B) Distorted octahedral
(C) Square pyramidal
(D) Trigonal bipyramidal
Answer: (B)
Explanation: XeF₆ has six bonding pairs and one lone pair on xenon, resulting in a distorted octahedral shape due to lone pair repulsion.
9. The catalyst used in the production of acetic acid from acetaldehyde is –
(A) Manganese acetate
(B) Platinum
(C) Nickel
(D) Copper
Answer: (A)
Explanation: Acetic acid (CH₃COOH) is produced by the oxidation of acetaldehyde (CH₃CHO) using manganese acetate as a catalyst in the presence of oxygen.
10. Which of the following ions is paramagnetic?
(A) Mg²⁺
(B) Fe³⁺
(C) Ca²⁺
(D) Sr²⁺
Answer: (B)
Explanation: Paramagnetic ions have unpaired electrons. Fe³⁺ ([Ar]3d⁵) has five unpaired electrons, while Mg²⁺, Ca²⁺, and Sr²⁺ have fully paired or empty orbitals.
11. The functional group in nitriles is –
(A) -CN
(B) -NC
(C) -NO₂
(D) -NH₂
Answer: (A)
Explanation: Nitriles are characterized by the -CN group, with a carbon-nitrogen triple bond bonded to a carbon chain.
12. The pH of a 0.1 M solution of a weak acid (Ka = 10⁻⁵) is –
(A) 2
(B) 3
(C) 4
(D) 5
Answer: (B)
Explanation: For a weak acid, [H⁺] = √(Ka × [HA]) = √(10⁻⁵ × 0.1) = √10⁻⁶ = 10⁻³ M. pH = -log(10⁻³) = 3.
13. The oxidation state of manganese in [Mn(CN)₆]⁴⁻ is –
(A) +2
(B) +3
(C) +4
(D) +6
Answer: (A)
Explanation: CN⁻ is a -1 ligand. The complex has a -4 charge. Let Mn = x. Then, x + 6(-1) = -4 → x – 6 = -4 → x = +2.
14. Which of the following is a secondary amine?
(A) CH₃NH₂
(B) (CH₃)₂NH
(C) (CH₃)₃N
(D) C₆H₅NH₂
Answer: (B)
Explanation: A secondary amine has two alkyl or aryl groups attached to nitrogen. (CH₃)₂NH (dimethylamine) is a secondary amine.
15. The enthalpy change of a reaction is –
(A) Always positive
(B) Always negative
(C) Can be positive or negative
(D) Zero for all reactions
Answer: (C)
Explanation: Enthalpy change (ΔH) can be positive (endothermic) or negative (exothermic), depending on whether heat is absorbed or released.
16. The metal used in the production of bronze is –
(A) Copper
(B) Zinc
(C) Tin
(D) Both (A) and (C)
Answer: (D)
Explanation: Bronze is an alloy of copper and tin, often used for its durability in statues and tools.
17. The monomer of bakelite is –
(A) Phenol and formaldehyde
(B) Ethylene
(C) Vinyl chloride
(D) Styrene
Answer: (A)
Explanation: Bakelite is a polymer formed by the condensation of phenol and formaldehyde, used in electrical insulators.
18. The rate of a first-order reaction is –
(A) Independent of concentration
(B) Proportional to concentration
(C) Proportional to square of concentration
(D) Inversely proportional to concentration
Answer: (B)
Explanation: For a first-order reaction, rate = k[A], meaning the rate is directly proportional to the reactant concentration.
19. Which of the following is an acidic salt?
(A) NaCl
(B) Na₂CO₃
(C) NH₄Cl
(D) Na₂SO₄
Answer: (C)
Explanation: NH₄Cl, formed from a weak base (NH₃) and a strong acid (HCl), is an acidic salt, producing H⁺ in solution.
20. The gas used in xenon arc lamps is –
(A) Neon
(B) Argon
(C) Xenon
(D) Helium
Answer: (C)
Explanation: Xenon arc lamps use xenon gas, which emits a bright white light when electrified, used in projectors and headlights.
21. The coordination number of Pb²⁺ in PbS (galena) is –
(A) 4
(B) 6
(C) 8
(D) 12
Answer: (B)
Explanation: In the galena (rock salt) structure, each Pb²⁺ ion is coordinated by six S²⁻ ions, giving a coordination number of 6.
22. Which of the following is a synthetic polymer?
(A) Chitin
(B) Starch
(C) Polyurethane
(D) Cellulose
Answer: (C)
Explanation: Polyurethane is a synthetic polymer, used in foams and coatings, while chitin, starch, and cellulose are natural polymers.
23. The unit of cell constant in conductivity measurements is –
(A) m⁻¹
(B) S m⁻¹
(C) m²
(D) S m²
Answer: (A)
Explanation: The cell constant (G*) is the ratio of electrode distance to area, with SI unit m⁻¹.
24. The compound responsible for the red color in glass is –
(A) Gold chloride
(B) Cobalt oxide
(C) Iron oxide
(D) Manganese dioxide
Answer: (A)
Explanation: Gold chloride (AuCl₃) imparts a red or ruby color to glass, used in decorative glassware.
25. The number of pi bonds in benzene (C₆H₆) is –
(A) 2
(B) 3
(C) 4
(D) 6
Answer: (B)
Explanation: Benzene has three C=C double bonds in its resonance structure, each with one sigma and one pi bond. Total pi bonds = 3.
26. Which of the following is a weak acid?
(A) H₂SO₄
(B) HNO₃
(C) HF
(D) HCl
Answer: (C)
Explanation: Hydrofluoric acid (HF) is a weak acid, partially dissociating in water, unlike strong acids H₂SO₄, HNO₃, and HCl.
27. The color of lithium chloride flame in a flame test is –
(A) Red
(B) Green
(C) Blue
(D) Yellow
Answer: (A)
Explanation: Lithium ions produce a red flame in a flame test due to electron transitions in the lithium atom.
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 third most abundant metal in Earth’s crust is –
(A) Aluminum
(B) Iron
(C) Calcium
(D) Magnesium
Answer: (C)
Explanation: Calcium (~3.6%) is the third most abundant metal in Earth’s crust, after aluminum (~8%) and iron (~5%).
30. The element used in the production of tracer bullets 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 tracer bullets for their visible glow when ignited.
31. The functional group in amides is –
(A) -CONH₂
(B) -COOH
(C) -CHO
(D) -OH
Answer: (A)
Explanation: Amides are characterized by the -CONH₂ group, with a carbonyl bonded to a nitrogen atom.
32. The rate of effusion 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 effusion is inversely proportional to √M, where M is the molecular weight.
33. Which of the following is an emulsion?
(A) Mayonnaise
(B) Fog
(C) Jelly
(D) Paint
Answer: (A)
Explanation: Mayonnaise is an emulsion, a colloid with oil droplets dispersed in water. Fog is an aerosol, jelly is a gel, and paint is a sol.
34. The oxidation number of sulfur in S₂O₈²⁻ is –
(A) +6
(B) +7
(C) +8
(D) +4
Answer: (B)
Explanation: In S₂O₈²⁻ (peroxydisulfate), O = -2, except in the peroxide bond (O-O, where O = -1). Let S = x. Then, 2x + 6(-2) + 2(-1) = -2 → 2x – 12 – 2 = -2 → 2x = 12 → x = +7.
35. The allotrope of sulfur used in vulcanization of rubber is –
(A) Rhombic sulfur
(B) Monoclinic sulfur
(C) Amorphous sulfur
(D) Plastic sulfur
Answer: (A)
Explanation: Rhombic sulfur, the most stable form, is used in the vulcanization of rubber to improve elasticity and strength.
36. The SI unit of colligative properties like osmotic pressure is –
(A) Pascal
(B) Joule
(C) Newton
(D) Meter
Answer: (A)
Explanation: Osmotic pressure, a colligative property, is a pressure measurement, with SI unit pascal (Pa).
37. The compound used as an antiseptic is –
(A) Sodium chloride
(B) Iodine tincture
(C) Chloroform
(D) Formaldehyde
Answer: (B)
Explanation: Iodine tincture (iodine in alcohol) is used as an antiseptic for its antimicrobial properties.
38. The reaction Mg + CuSO₄ → MgSO₄ + Cu is an example of –
(A) Combination
(B) Decomposition
(C) Displacement
(D) Double displacement
Answer: (C)
Explanation: This is a displacement reaction, where magnesium displaces copper from copper sulfate due to its higher reactivity.
39. The element with atomic number 16 belongs to –
(A) Alkali metals
(B) Halogens
(C) Chalcogens
(D) Noble gases
Answer: (C)
Explanation: Atomic number 16 corresponds to sulfur, in group 16 (chalcogens).
40. The osmotic pressure of a solution increases with –
(A) Decreasing temperature
(B) Increasing temperature
(C) Decreasing concentration
(D) Decreasing volume
Answer: (B)
Explanation: Osmotic pressure (π = CRT) increases with temperature, as it is directly proportional to T (Kelvin).
41. The compound responsible for the smell of apples is –
(A) Ethyl acetate
(B) Hexyl acetate
(C) Ethanol
(D) Acetone
Answer: (B)
Explanation: Hexyl acetate is an ester responsible for the apple-like odor.
42. The crystal structure of graphite is –
(A) Hexagonal
(B) Cubic
(C) Tetragonal
(D) Orthorhombic
Answer: (A)
Explanation: Graphite has a hexagonal crystal structure, with carbon atoms arranged in layered sheets.
43. The gas used in MRI scanners is –
(A) Helium
(B) Neon
(C) Argon
(D) Xenon
Answer: (A)
Explanation: Liquid helium is used in MRI scanners to cool superconducting magnets to very low temperatures.
44. The common name for heptanoic acid is –
(A) Caproic acid
(B) Enanthic acid
(C) Valeric acid
(D) Butyric acid
Answer: (B)
Explanation: Heptanoic acid (CH₃(CH₂)₅COOH) is commonly known as enanthic acid.
45. The phenomenon of migration of ions in an electric field is called –
(A) Tyndall effect
(B) Brownian motion
(C) Electrophoresis
(D) Coagulation
Answer: (C)
Explanation: Electrophoresis is the movement of charged particles, like ions or colloids, in an electric field.
46. The element used in smoke detectors is –
(A) Americium
(B) Uranium
(C) Plutonium
(D) Radium
Answer: (A)
Explanation: Americium-241, an alpha emitter, is used in smoke detectors to ionize air and detect smoke particles.
47. The formula of baking soda is –
(A) Na₂CO₃
(B) NaHCO₃
(C) CaCO₃
(D) Na₂SO₄
Answer: (B)
Explanation: Baking soda is sodium bicarbonate (NaHCO₃), used as a leavening agent in baking.
48. The oxidation number of nitrogen in NO₃⁻ is –
(A) +3
(B) +4
(C) +5
(D) +6
Answer: (C)
Explanation: In NO₃⁻ (nitrate), O = -2. Let N = x. Then, x + 3(-2) = -1 → x – 6 = -1 → x = +5.
49. Which of the following is a buffer solution?
(A) HNO₃ + NaNO₃
(B) NH₄OH + NH₄Cl
(C) HCl + NaCl
(D) NaOH + NaCl
Answer: (B)
Explanation: A buffer requires a weak base and its conjugate acid. NH₄OH (weak base) and NH₄Cl (conjugate acid) form a buffer.
50. The IUPAC name of CH₃CH₂CH₂OH is –
(A) Propan-1-ol
(B) Propan-2-ol
(C) Ethanol
(D) Butan-1-ol
Answer: (A)
Explanation: CH₃CH₂CH₂OH has three carbon atoms with the hydroxyl group on the first carbon, so its IUPAC name is propan-1-ol.