1. The hybridization of the central atom in [Ni(CN)₄]²⁻ is –
(A) sp³
(B) dsp²
(C) sp³d
(D) sp³d²
Answer: (B)
Explanation: Nickel in [Ni(CN)₄]²⁻ forms four bonds with cyanide ligands in a square planar geometry, requiring four hybrid orbitals. Ni²⁺ uses dsp² hybridization for this arrangement.
2. Which gas is used in the production of hydrochloric acid?
(A) Chlorine
(B) Hydrogen
(C) Nitrogen
(D) Both (A) and (B)
Answer: (D)
Explanation: Hydrochloric acid (HCl) is produced by reacting hydrogen (H₂) and chlorine (Cl₂) gases, followed by dissolution in water.
3. The bond angle in the NH₃ molecule is approximately –
(A) 90°
(B) 104.5°
(C) 107°
(D) 120°
Answer: (C)
Explanation: NH₃ has a trigonal pyramidal shape with three bonding pairs and one lone pair on nitrogen, resulting in a bond angle of ~107° due to lone pair repulsion, per VSEPR theory.
4. The primary source of sulfur dioxide in the atmosphere is –
(A) Volcanic eruptions
(B) Photosynthesis
(C) Industrial emissions
(D) Both (A) and (C)
Answer: (D)
Explanation: Sulfur dioxide (SO₂) is released from volcanic eruptions and industrial activities (e.g., burning fossil fuels), contributing to acid rain.
5. Which of the following is a bidentate ligand?
(A) Ammonia
(B) Acetylacetonate
(C) Chloride
(D) Water
Answer: (B)
Explanation: Acetylacetonate (acac) is a bidentate ligand, binding to a metal ion at two oxygen atoms, unlike ammonia, chloride, or water, which are monodentate.
6. The rate of a second-order reaction is proportional to –
(A) [Reactant]
(B) [Reactant]²
(C) 1/[Reactant]
(D) [Catalyst]
Answer: (B)
Explanation: For a second-order reaction, the rate law is rate = k[A]² or k[A][B], so the rate is proportional to the square of the reactant concentration or the product of two concentrations.
7. The element with the highest electron affinity in group 17 is –
(A) Fluorine
(B) Chlorine
(C) Bromine
(D) Iodine
Answer: (B)
Explanation: Electron affinity peaks at chlorine in group 17 due to its optimal balance of nuclear charge and electron repulsion, unlike fluorine, which has higher repulsion due to its smaller size.
8. The shape of the BrF₃ molecule is –
(A) Trigonal planar
(B) T-shaped
(C) Tetrahedral
(D) Linear
Answer: (B)
Explanation: BrF₃ has three bonding pairs and two lone pairs on bromine, resulting in a T-shaped molecular geometry from a trigonal bipyramidal electron arrangement.
9. The catalyst used in the production of nitric oxide in the Ostwald process is –
(A) Platinum
(B) Iron
(C) Nickel
(D) Copper
Answer: (A)
Explanation: The Ostwald process oxidizes ammonia to nitric oxide (4NH₃ + 5O₂ → 4NO + 6H₂O) using a platinum-rhodium catalyst.
10. Which of the following ions is paramagnetic?
(A) Sc³⁺
(B) Ti³⁺
(C) Zn²⁺
(D) Ca²⁺
Answer: (B)
Explanation: Paramagnetic ions have unpaired electrons. Ti³⁺ ([Ar]3d¹) has one unpaired electron, while Sc³⁺, Zn²⁺, and Ca²⁺ have fully paired or empty orbitals.
11. The functional group in isocyanides is –
(A) -NC
(B) -CN
(C) -NO₂
(D) -NH₂
Answer: (A)
Explanation: Isocyanides are characterized by the -NC group, with nitrogen bonded to the carbon chain and a lone pair on carbon, unlike cyanides (-CN).
12. The pH of a 0.001 M solution of a weak acid (Ka = 10⁻⁵) is –
(A) 3
(B) 4
(C) 5
(D) 6
Answer: (B)
Explanation: For a weak acid, [H⁺] = √(Ka × [HA]) = √(10⁻⁵ × 0.001) = √10⁻⁸ ≈ 10⁻⁴ M. pH = -log(10⁻⁴) = 4.
13. The oxidation state of cobalt in [Co(NH₃)₅Cl]²⁺ is –
(A) +1
(B) +2
(C) +3
(D) +4
Answer: (C)
Explanation: NH₃ is neutral, Cl⁻ is -1. The complex has a +2 charge. Let Co = x. Then, x + 5(0) + (-1) = +2 → x – 1 = +2 → x = +3.
14. Which of the following is a primary alcohol?
(A) CH₃OH
(B) (CH₃)₂CHOH
(C) (CH₃)₃COH
(D) C₆H₅OH
Answer: (A)
Explanation: A primary alcohol has the -OH group on a carbon bonded to one other carbon. CH₃OH (methanol) is a primary alcohol.
15. The first law of thermodynamics is a statement of –
(A) Entropy increase
(B) Conservation of energy
(C) Heat flow direction
(D) Spontaneity of reactions
Answer: (B)
Explanation: The first law of thermodynamics states that the total energy of an isolated system is conserved (ΔU = q + w).
16. The metal used in the production of pewter is –
(A) Tin
(B) Zinc
(C) Copper
(D) Iron
Answer: (A)
Explanation: Pewter is an alloy primarily composed of tin, often mixed with small amounts of copper or antimony.
17. The monomer of polyacrylonitrile is –
(A) Acrylonitrile
(B) Ethylene
(C) Vinyl chloride
(D) Styrene
Answer: (A)
Explanation: Polyacrylonitrile is a polymer of acrylonitrile (CH₂=CHCN), used in fibers like acrylic.
18. The rate constant of a first-order reaction depends on –
(A) Initial concentration
(B) Temperature
(C) Volume
(D) Pressure
Answer: (B)
Explanation: The rate constant (k) of a first-order reaction depends on temperature, as described by the Arrhenius equation (k = Ae^(-Ea/RT)).
19. Which of the following is an amphoteric oxide?
(A) CO₂
(B) ZnO
(C) SO₃
(D) P₂O₅
Answer: (B)
Explanation: ZnO is amphoteric, reacting with both acids (to form salts) and bases (to form zincates), unlike CO₂, SO₃, and P₂O₅, which are acidic.
20. The gas used in plasma displays is –
(A) Helium
(B) Neon
(C) Xenon
(D) Both (B) and (C)
Answer: (D)
Explanation: Plasma displays use a mixture of neon and xenon gases to produce light when electrified.
21. The coordination number of Ca²⁺ in fluorite (CaF₂) is –
(A) 4
(B) 6
(C) 8
(D) 12
Answer: (C)
Explanation: In the fluorite structure, each Ca²⁺ ion is surrounded by eight F⁻ ions, giving a coordination number of 8.
22. Which of the following is a biodegradable polymer?
(A) Polyvinyl chloride
(B) Polyethylene
(C) Poly(lactic acid)
(D) Polystyrene
Answer: (C)
Explanation: Poly(lactic acid) (PLA) is biodegradable, derived from renewable resources, unlike PVC, polyethylene, and polystyrene.
23. The unit of van’t Hoff factor is –
(A) mol/kg
(B) Dimensionless
(C) mol/L
(D) L/mol
Answer: (B)
Explanation: The van’t Hoff factor (i) is the ratio of actual to expected colligative properties, a dimensionless quantity.
24. The compound responsible for the green color in fireworks is –
(A) Barium chloride
(B) Strontium nitrate
(C) Copper chloride
(D) Potassium chloride
Answer: (A)
Explanation: Barium chloride produces a green flame in fireworks due to the emission spectrum of barium ions.
25. The number of pi bonds in acetylene (C₂H₂) is –
(A) 1
(B) 2
(C) 3
(D) 4
Answer: (B)
Explanation: Acetylene (HC≡CH) has one triple bond, consisting of one sigma and two pi bonds, so the number of pi bonds is 2.
26. Which of the following is a weak electrolyte?
(A) KCl
(B) H₂SO₄
(C) HCOOH
(D) NaOH
Answer: (C)
Explanation: Formic acid (HCOOH) is a weak electrolyte, partially dissociating in water, unlike strong electrolytes KCl, H₂SO₄, and NaOH.
27. The color of anhydrous copper sulfate (CuSO₄) is –
(A) Blue
(B) Green
(C) White
(D) Yellow
Answer: (C)
Explanation: Anhydrous CuSO₄ is white, while its hydrated form (CuSO₄·5H₂O) is blue due to water coordination with Cu²⁺ ions.
28. The process of converting a solid directly to a gas is called –
(A) Sublimation
(B) Evaporation
(C) Condensation
(D) Deposition
Answer: (A)
Explanation: Sublimation is the direct transition from solid to gas, such as dry ice (CO₂) vaporizing.
29. The most abundant gas in Earth’s atmosphere is –
(A) Oxygen
(B) Nitrogen
(C) Carbon dioxide
(D) Argon
Answer: (B)
Explanation: Nitrogen (~78%) is the most abundant gas in Earth’s atmosphere, followed by oxygen (~21%).
30. The element used in the production of sparklers is –
(A) Magnesium
(B) Aluminum
(C) Iron
(D) All of the above
Answer: (D)
Explanation: Sparklers use magnesium, aluminum, and iron to produce bright sparks when ignited.
31. The functional group in carboxylic acids is –
(A) -OH
(B) -COOH
(C) -CHO
(D) -COOR
Answer: (B)
Explanation: Carboxylic acids are characterized by the -COOH group, with a carbonyl and hydroxyl group on the same carbon.
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 an emulsion?
(A) Butter
(B) Fog
(C) Jelly
(D) Paint
Answer: (A)
Explanation: Butter is an emulsion, a colloid with water droplets dispersed in fat. Fog is an aerosol, jelly is a gel, and paint is a sol.
34. The oxidation number of sulfur in SO₃²⁻ is –
(A) +2
(B) +4
(C) +6
(D) +3
Answer: (B)
Explanation: In SO₃²⁻ (sulfite), O = -2. Let S = x. Then, x + 3(-2) = -2 → x – 6 = -2 → x = +4.
35. The allotrope of carbon used in cutting tools is –
(A) Graphite
(B) Diamond
(C) Fullerene
(D) Charcoal
Answer: (B)
Explanation: Diamond, due to its extreme hardness from its tetrahedral covalent structure, is used in cutting tools.
36. The SI unit of viscosity is –
(A) Pa·s
(B) N/m
(C) J/m²
(D) kg/m
Answer: (A)
Explanation: Viscosity is the resistance to flow, with SI unit pascal-second (Pa·s).
37. The compound used as a disinfectant is –
(A) Sodium chloride
(B) Hydrogen peroxide
(C) Ethanol
(D) Both (B) and (C)
Answer: (D)
Explanation: Hydrogen peroxide (H₂O₂) and ethanol (C₂H₅OH) are used as disinfectants due to their antimicrobial properties.
38. The reaction 2Al + 3CuSO₄ → Al₂(SO₄)₃ + 3Cu is an example of –
(A) Combination
(B) Decomposition
(C) Displacement
(D) Double displacement
Answer: (C)
Explanation: This is a displacement reaction, where aluminum displaces copper from copper sulfate due to its higher reactivity.
39. The element with atomic number 12 belongs to –
(A) Alkali metals
(B) Halogens
(C) Noble gases
(D) Alkaline earth metals
Answer: (D)
Explanation: Atomic number 12 corresponds to magnesium, in group 2 (alkaline earth metals).
40. The freezing point of a liquid decreases with –
(A) Increasing pressure
(B) Decreasing pressure
(C) Increasing temperature
(D) Decreasing volume
Answer: (B)
Explanation: For most liquids, decreasing pressure lowers the freezing point, as less pressure favors the less dense liquid phase, per Le Chatelier’s principle.
41. The compound responsible for the smell of nail polish remover is –
(A) Acetone
(B) Ethanol
(C) Toluene
(D) Formaldehyde
Answer: (A)
Explanation: Acetone (CH₃COCH₃) is the primary component of nail polish remover, giving it a characteristic odor.
42. The crystal structure of zinc sulfide (ZnS) in wurtzite form is –
(A) Hexagonal
(B) Cubic
(C) Orthorhombic
(D) Tetragonal
Answer: (A)
Explanation: The wurtzite form of ZnS has a hexagonal crystal structure, with tetrahedral coordination of Zn²⁺ and S²⁻ ions.
43. The gas used in deep-sea diving is –
(A) Helium
(B) Neon
(C) Argon
(D) Oxygen
Answer: (A)
Explanation: Helium is used in deep-sea diving (e.g., in heliox mixtures) to reduce nitrogen narcosis and oxygen toxicity.
44. The common name for ethanoic acid is –
(A) Formic acid
(B) Acetic acid
(C) Propionic acid
(D) Butyric acid
Answer: (B)
Explanation: Ethanoic acid (CH₃COOH) is commonly known as acetic acid, found in vinegar.
45. The phenomenon of separation of charge in a molecule is called –
(A) Dipole moment
(B) Electronegativity
(C) Polarization
(D) Ionization
Answer: (A)
Explanation: Dipole moment measures the separation of positive and negative charges in a molecule, indicating its polarity.
46. The element used in solar cells is –
(A) Silicon
(B) Germanium
(C) Gallium
(D) All of the above
Answer: (D)
Explanation: Silicon, germanium, and gallium (in compounds like gallium arsenide) are used in solar cells for their semiconductor properties.
47. The formula of washing soda is –
(A) Na₂CO₃
(B) NaHCO₃
(C) CaCO₃
(D) Na₂SO₄
Answer: (A)
Explanation: Washing soda is sodium carbonate (Na₂CO₃), used as a cleaning agent.
48. The oxidation number of chlorine in ClO₄⁻ is –
(A) +5
(B) +6
(C) +7
(D) +4
Answer: (C)
Explanation: In ClO₄⁻ (perchlorate), O = -2. Let Cl = x. Then, x + 4(-2) = -1 → x – 8 = -1 → x = +7.
49. Which of the following is not a buffer solution?
(A) NH₄OH + NH₄Cl
(B) CH₃COOH + CH₃COONa
(C) HCl + NaCl
(D) H₃PO₄ + NaH₂PO₄
Answer: (C)
Explanation: A buffer requires a weak acid/base and its conjugate. HCl + NaCl contains a strong acid, so it’s not a buffer.
50. The IUPAC name of CH₃CH₂OCH₃ is –
(A) Methoxyethane
(B) Ethoxymethane
(C) Methyl ethyl ether
(D) Dimethyl ether
Answer: (A)
Explanation: CH₃CH₂OCH₃ is an ether with a methoxy group (CH₃O-) and an ethyl group (C₂H₅-), so its IUPAC name is methoxyethane.