1. The hybridization of the central atom in IF₇ is –
(A) sp³
(B) sp³d²
(C) sp³d³
(D) dsp²
Answer: (C)
Explanation: Iodine in IF₇ forms seven bonds with fluorine, requiring seven hybrid orbitals. This is achieved through sp³d³ hybridization, resulting in a pentagonal bipyramidal shape per VSEPR theory.
2. Which gas is used in the production of glass?
(A) Nitrogen
(B) Oxygen
(C) Carbon dioxide
(D) Argon
Answer: (D)
Explanation: Argon is used in glass production to create an inert atmosphere, preventing oxidation and improving the quality of the glass.
3. The bond angle in the H₂S molecule is approximately –
(A) 90°
(B) 104.5°
(C) 109.5°
(D) 120°
Answer: (A)
Explanation: H₂S has a bent shape with two bonding pairs and two lone pairs on sulfur, leading to a bond angle of ~90° due to strong lone pair repulsion, as per VSEPR theory.
4. The primary source of chlorofluorocarbons (CFCs) in the atmosphere is –
(A) Volcanic eruptions
(B) Industrial refrigerants
(C) Combustion of fossil fuels
(D) Agricultural runoff
Answer: (B)
Explanation: CFCs, used in refrigerants and aerosols, are synthetic compounds released primarily from industrial and consumer applications, contributing to ozone depletion.
5. Which of the following is a chelating ligand?
(A) Cl⁻
(B) NH₃
(C) Oxalate
(D) H₂O
Answer: (C)
Explanation: A chelating ligand forms multiple coordinate bonds with a metal ion. Oxalate (C₂O₄²⁻) is bidentate, forming a five-membered ring with the metal, unlike monodentate Cl⁻, NH₃, or H₂O.
6. The molecularity of a reaction is –
(A) The number of reactants in the rate law
(B) The number of molecules in the rate-determining step
(C) The sum of the reaction orders
(D) The number of products formed
Answer: (B)
Explanation: Molecularity is the number of molecules or ions participating in the rate-determining step of an elementary reaction.
7. The element with the highest electronegativity in group 16 is –
(A) Oxygen
(B) Sulfur
(C) Selenium
(D) Tellurium
Answer: (A)
Explanation: Electronegativity decreases down a group. Oxygen, at the top of group 16, has the highest electronegativity (3.44 on the Pauling scale).
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, leading to a distorted octahedral shape due to lone pair distortion in the octahedral electron geometry.
9. The catalyst used in the synthesis of methanol is –
(A) Copper-based catalyst
(B) Platinum
(C) Nickel
(D) Iron
Answer: (A)
Explanation: Methanol synthesis (CO + 2H₂ → CH₃OH) uses a copper-based catalyst (e.g., Cu/ZnO/Al₂O₃) under high pressure and temperature.
10. Which of the following ions is diamagnetic?
(A) Mn²⁺
(B) Fe²⁺
(C) Cd²⁺
(D) Ni²⁺
Answer: (C)
Explanation: Diamagnetic ions have all paired electrons. Cd²⁺ ([Kr]4d¹⁰) has a fully filled d-subshell, while Mn²⁺, Fe²⁺, and Ni²⁺ have unpaired electrons, making them paramagnetic.
11. The functional group in nitriles is –
(A) -CN
(B) -NH₂
(C) -NO₂
(D) -OH
Answer: (A)
Explanation: Nitriles are characterized by the -CN group, with a carbon-nitrogen triple bond.
12. The pOH of a 0.1 M solution of a strong base is –
(A) 1
(B) 2
(C) 3
(D) 4
Answer: (A)
Explanation: A strong base fully dissociates. For 0.1 M base, [OH⁻] = 0.1 M = 10⁻¹ M. pOH = -log(10⁻¹) = 1. (pH = 14 – pOH = 13).
13. The oxidation state of nickel in [Ni(CN)₄]²⁻ is –
(A) +1
(B) +2
(C) +3
(D) +4
Answer: (B)
Explanation: CN⁻ is a -1 ligand. The complex has a -2 charge. Let Ni = x. Then, x + 4(-1) = -2 → x – 4 = -2 → x = +2.
14. Which of the following is a primary halide?
(A) CH₃Cl
(B) (CH₃)₂CHCl
(C) (CH₃)₃CCl
(D) CH₂=CHCl
Answer: (A)
Explanation: A primary halide has the halogen on a carbon bonded to one other carbon. CH₃Cl (methyl chloride) is a primary halide.
15. The standard enthalpy of formation is defined at –
(A) 0 K
(B) 273 K
(C) 298 K
(D) 373 K
Answer: (C)
Explanation: The standard enthalpy of formation (ΔH_f°) is the enthalpy change when one mole of a compound is formed from its elements in their standard states at 298 K and 1 atm.
16. The metal used in the production of bronze is –
(A) Zinc
(B) Tin
(C) Aluminum
(D) Iron
Answer: (B)
Explanation: Bronze is an alloy of copper and tin, known for its strength and corrosion resistance.
17. The monomer of buna-S rubber is –
(A) Styrene and butadiene
(B) Ethylene
(C) Vinyl chloride
(D) Isoprene
Answer: (A)
Explanation: Buna-S (styrene-butadiene rubber) is a copolymer of styrene and 1,3-butadiene, used in tires.
18. The rate constant of a second-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: (C)
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 an acidic salt?
(A) Na₂SO₄
(B) NaH₂PO₄
(C) KCl
(D) Na₂CO₃
Answer: (B)
Explanation: NaH₂PO₄, formed from a weak acid (H₃PO₄) and a strong base (NaOH), is an acidic salt, producing H⁺ in solution.
20. The gas used in arc welding is –
(A) Argon
(B) Neon
(C) Helium
(D) Both (A) and (C)
Answer: (D)
Explanation: Argon and helium are used as shielding gases in arc welding to protect the weld from atmospheric contamination.
21. The coordination number of Fe²⁺ in FeS (wurtzite structure) is –
(A) 4
(B) 6
(C) 8
(D) 12
Answer: (A)
Explanation: In the wurtzite structure of FeS, each Fe²⁺ ion is tetrahedrally coordinated by four S²⁻ ions, giving a coordination number of 4.
22. Which of the following is a biodegradable polymer?
(A) Polythene
(B) Polyvinyl chloride
(C) Polyhydroxybutyrate
(D) Polystyrene
Answer: (C)
Explanation: Polyhydroxybutyrate (PHB) is a biodegradable polymer produced by microorganisms, unlike polythene, PVC, and polystyrene.
23. The unit of electrochemical equivalent is –
(A) g/C
(B) C/g
(C) S/m
(D) mol/C
Answer: (A)
Explanation: Electrochemical equivalent is the mass of a substance deposited per coulomb of charge, with unit g/C.
24. The compound responsible for the white color in fireworks is –
(A) Magnesium
(B) Sodium chloride
(C) Barium chloride
(D) Strontium nitrate
Answer: (A)
Explanation: Magnesium produces a bright white flame in fireworks due to its intense emission spectrum.
25. The number of sigma bonds in ethene (C₂H₄) is –
(A) 3
(B) 4
(C) 5
(D) 6
Answer: (C)
Explanation: Ethene (H₂C=CH₂) has one C=C double bond (1 sigma + 1 pi) and four C-H single bonds (4 sigma). Total sigma bonds = 1 + 4 = 5.
26. Which of the following is a strong base?
(A) NH₃
(B) Ca(OH)₂
(C) CH₃NH₂
(D) NaOH
Answer: (D)
Explanation: NaOH is a strong base, fully dissociating in water, unlike NH₃ and CH₃NH₂ (weak bases) and Ca(OH)₂ (moderately strong due to lower solubility).
27. The color of potassium permanganate (KMnO₄) solution is –
(A) Purple
(B) Green
(C) Yellow
(D) Colorless
Answer: (A)
Explanation: KMnO₄ solution is purple due to charge transfer transitions involving the MnO₄⁻ ion.
28. The process of converting a gas directly 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, without passing through the liquid phase.
29. The most abundant element in Earth’s crust is –
(A) Oxygen
(B) Silicon
(C) Aluminum
(D) Iron
Answer: (A)
Explanation: Oxygen is the most abundant element in Earth’s crust (~46%), primarily in compounds like silicates and oxides.
30. The element used in the production of gunpowder is –
(A) Sulfur
(B) Phosphorus
(C) Potassium nitrate
(D) Both (A) and (C)
Answer: (D)
Explanation: Gunpowder contains sulfur and potassium nitrate (KNO₃), along with charcoal, for its explosive properties.
31. The functional group in amides is –
(A) -CONH₂
(B) -COOH
(C) -CHO
(D) -CN
Answer: (A)
Explanation: Amides are characterized by the -CONH₂ group, with a carbonyl bonded to a nitrogen atom.
32. The rate of diffusion 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 diffusion is inversely proportional to √M, where M is the molecular weight.
33. Which of the following is a gel?
(A) Jelly
(B) Milk
(C) Fog
(D) Sugar syrup
Answer: (A)
Explanation: Jelly is a gel, a colloid with a solid matrix trapping a liquid. Milk is an emulsion, fog is an aerosol, and sugar syrup is a solution.
34. The oxidation number of chromium in CrO₄²⁻ is –
(A) +4
(B) +5
(C) +6
(D) +7
Answer: (C)
Explanation: In CrO₄²⁻, O = -2. Let Cr = x. Then, x + 4(-2) = -2 → x – 8 = -2 → x = +6.
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 vulcanization to cross-link rubber, improving its strength and elasticity.
36. The SI unit of molarity is –
(A) mol/L
(B) mol/kg
(C) mol/m³
(D) kg/mol
Answer: (A)
Explanation: Molarity is moles of solute per liter of solution, with SI unit mol/L.
37. The compound used as a fungicide is –
(A) Sodium chloride
(B) Copper sulfate
(C) Ethanol
(D) Formaldehyde
Answer: (B)
Explanation: Copper sulfate (CuSO₄) is used as a fungicide, particularly in agriculture (e.g., Bordeaux mixture).
38. The reaction Mg + 2HCl → MgCl₂ + H₂ is an example of –
(A) Combination
(B) Decomposition
(C) Displacement
(D) Double displacement
Answer: (C)
Explanation: This is a displacement reaction, where magnesium displaces hydrogen from HCl due to its higher reactivity.
39. The element with atomic number 9 belongs to –
(A) Alkali metals
(B) Halogens
(C) Noble gases
(D) Alkaline earth metals
Answer: (B)
Explanation: Atomic number 9 corresponds to fluorine, in group 17 (halogens).
40. The melting point of a substance increases with –
(A) Decreasing pressure
(B) Increasing pressure
(C) Decreasing temperature
(D) Increasing volume
Answer: (B)
Explanation: For most substances, increasing pressure raises the melting point by favoring the denser solid phase, per Le Chatelier’s principle.
41. The compound responsible for the smell of burnt matches is –
(A) Sulfur dioxide
(B) Hydrogen sulfide
(C) Carbon monoxide
(D) Nitrogen dioxide
Answer: (A)
Explanation: Sulfur dioxide (SO₂), produced during match combustion, gives the characteristic smell of burnt matches.
42. The crystal structure of graphite is –
(A) Tetrahedral
(B) Hexagonal
(C) Cubic
(D) Orthorhombic
Answer: (B)
Explanation: Graphite has a layered hexagonal structure, with strong covalent bonds within layers and weak van der Waals forces between them.
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 near absolute zero.
44. The common name for butanedioic acid is –
(A) Malonic acid
(B) Oxalic acid
(C) Succinic acid
(D) Glutaric acid
Answer: (C)
Explanation: Butanedioic acid (HOOC-CH₂-CH₂-COOH) is commonly known as succinic acid, used in biochemical processes.
45. The phenomenon of movement of colloidal particles under an electric field is –
(A) Tyndall effect
(B) Brownian motion
(C) Electrophoresis
(D) Coagulation
Answer: (C)
Explanation: Electrophoresis is the movement of charged colloidal particles in an electric field, used in techniques like gel electrophoresis.
46. The element used in barometers is –
(A) Mercury
(B) Gallium
(C) Sodium
(D) Cesium
Answer: (A)
Explanation: Mercury is used in barometers due to its high density and liquid state, allowing accurate pressure measurements.
47. The formula of baking soda is –
(A) Na₂CO₃
(B) NaHCO₃
(C) CaCO₃
(D) Ca(OH)₂
Answer: (B)
Explanation: Baking soda is sodium bicarbonate (NaHCO₃), used in cooking and as an antacid.
48. The oxidation number of nitrogen in N₂H₄ is –
(A) -2
(B) +2
(C) 0
(D) +4
Answer: (A)
Explanation: In N₂H₄ (hydrazine), H = +1. Let N = x. Then, 2x + 4(+1) = 0 → 2x + 4 = 0 → x = -2.
49. Which of the following is not a redox reaction?
(A) 2H₂ + O₂ → 2H₂O
(B) NaOH + HCl → NaCl + H₂O
(C) Zn + CuSO₄ → ZnSO₄ + Cu
(D) 2KClO₃ → 2KCl + 3O₂
Answer: (B)
Explanation: NaOH + HCl → NaCl + H₂O is a neutralization reaction, not involving electron transfer. The others are redox reactions with changes in oxidation states.
50. The IUPAC name of CH₃CH₂CH₂OH is –
(A) Methanol
(B) Ethanol
(C) Propan-1-ol
(D) Butan-1-ol
Answer: (C)
Explanation: CH₃CH₂CH₂OH has three carbon atoms and a hydroxyl group on the first carbon, so its IUPAC name is propan-1-ol.