1. The hybridization of the central atom in XeF₂ is –
(A) sp³
(B) sp³d
(C) sp²
(D) sp³d²
Answer: (B)
Explanation: Xenon in XeF₂ forms two bonds with fluorine and has three lone pairs, requiring five hybrid orbitals. This is achieved through sp³d hybridization, resulting in a linear shape due to lone pair repulsion in the trigonal bipyramidal electron geometry.
2. Which gas is used in the production of fertilizers like ammonium nitrate?
(A) Nitrogen
(B) Oxygen
(C) Ammonia
(D) Carbon dioxide
Answer: (C)
Explanation: Ammonia (NH₃) is a key raw material in producing ammonium nitrate (NH₄NO₃) via neutralization with nitric acid in fertilizer manufacturing.
3. The bond angle in the SO₂ molecule is approximately –
(A) 90°
(B) 109.5°
(C) 120°
(D) 180°
Answer: (C)
Explanation: SO₂ has a bent shape with two bonding pairs and one lone pair on sulfur, leading to a bond angle of ~120°, as predicted by VSEPR theory.
4. The primary source of carbon monoxide in the atmosphere is –
(A) Volcanic activity
(B) Incomplete combustion
(C) Photosynthesis
(D) Ocean emissions
Answer: (B)
Explanation: Carbon monoxide (CO) is primarily produced from incomplete combustion of fossil fuels in vehicles, industries, and fires, contributing to air pollution.
5. Which of the following is a bidentate ligand?
(A) NH₃
(B) Cl⁻
(C) Ethylenediamine
(D) H₂O
Answer: (C)
Explanation: A bidentate ligand binds to a metal ion at two sites. Ethylenediamine (H₂NCH₂CH₂NH₂) has two nitrogen atoms that can coordinate, unlike NH₃, Cl⁻, or H₂O, which are monodentate.
6. The order of a reaction is determined by –
(A) Temperature
(B) Catalyst
(C) Sum of the powers of concentration terms in the rate law
(D) Activation energy
Answer: (C)
Explanation: The order of a reaction is the sum of the exponents of the concentration terms in the rate law (e.g., rate = k[A]^m[B]^n, order = m + n).
7. The element with the highest melting point in group 1 is –
(A) Lithium
(B) Sodium
(C) Potassium
(D) Cesium
Answer: (A)
Explanation: Melting point decreases down group 1 due to weaker metallic bonding. Lithium, at the top, has the highest melting point among alkali metals.
8. The shape of the ClF₃ molecule is –
(A) Trigonal planar
(B) T-shaped
(C) Tetrahedral
(D) Linear
Answer: (B)
Explanation: ClF₃ has three bonding pairs and two lone pairs around chlorine, resulting in a T-shaped molecular geometry from a trigonal bipyramidal electron arrangement.
9. The catalyst used in the Deacon process for chlorine production is –
(A) Copper(II) chloride
(B) Platinum
(C) Nickel
(D) Iron
Answer: (A)
Explanation: The Deacon process (4HCl + O₂ → 2Cl₂ + 2H₂O) uses copper(II) chloride (CuCl₂) as a catalyst to oxidize HCl to chlorine.
10. Which of the following ions is diamagnetic?
(A) Co²⁺
(B) Ni²⁺
(C) Zn²⁺
(D) Cr³⁺
Answer: (C)
Explanation: Diamagnetic ions have all paired electrons. Zn²⁺ ([Ar]3d¹⁰) has a fully filled d-subshell, while Co²⁺, Ni²⁺, and Cr³⁺ have unpaired electrons, making them paramagnetic.
11. The functional group in alcohols is –
(A) -CHO
(B) -OH
(C) -COOH
(D) -NH₂
Answer: (B)
Explanation: Alcohols are characterized by the hydroxyl group (-OH) attached to a carbon atom.
12. The pH of a 0.001 M solution of a weak acid (Ka = 10⁻⁴) is –
(A) 2
(B) 3
(C) 4
(D) 5
Answer: (B)
Explanation: For a weak acid, [H⁺] = √(Ka × [HA]) = √(10⁻⁴ × 0.001) = √10⁻⁷ ≈ 3.16 × 10⁻⁴ M. pH = -log(3.16 × 10⁻⁴) ≈ 3.5, rounded to 3.
13. The oxidation state of iron in Fe(CO)₅ is –
(A) 0
(B) +2
(C) +3
(D) +5
Answer: (A)
Explanation: In Fe(CO)₅, CO is a neutral ligand, so the oxidation state of iron is 0, typical for metal carbonyls.
14. Which of the following is a secondary amine?
(A) CH₃NH₂
(B) (CH₃)₂NH
(C) (CH₃)₃N
(D) NH₃
Answer: (B)
Explanation: A secondary amine has two alkyl groups attached to nitrogen. (CH₃)₂NH (dimethylamine) is a secondary amine.
15. The third law of thermodynamics states that –
(A) Energy is conserved
(B) Entropy of a perfect crystal at 0 K is zero
(C) Heat flows from hot to cold
(D) Work equals heat
Answer: (B)
Explanation: The third law states that the entropy of a perfect crystal at absolute zero (0 K) is zero, as it has a single microstate.
16. The metal used in the production of stainless steel is –
(A) Chromium
(B) Copper
(C) Zinc
(D) Aluminum
Answer: (A)
Explanation: Chromium is added to steel to form stainless steel, enhancing corrosion resistance due to the formation of a protective oxide layer.
17. The monomer of teflon is –
(A) Vinyl chloride
(B) Tetrafluoroethylene
(C) Styrene
(D) Ethylene
Answer: (B)
Explanation: Teflon (PTFE) is a polymer of tetrafluoroethylene (C₂F₄), known for its non-stick properties.
18. The half-life of a second-order reaction is –
(A) Independent of initial concentration
(B) Inversely proportional to initial concentration
(C) Proportional to rate constant
(D) Independent of rate constant
Answer: (B)
Explanation: For a second-order reaction, t₁/₂ = 1/(k[A]₀), which is inversely proportional to the initial concentration ([A]₀).
19. Which of the following is a basic salt?
(A) NaCl
(B) NaHCO₃
(C) NH₄Cl
(D) KNO₃
Answer: (B)
Explanation: NaHCO₃ (sodium bicarbonate) is a basic salt, formed from a strong base (NaOH) and a weak acid (H₂CO₃), producing OH⁻ in solution.
20. The gas used in refrigeration systems historically was –
(A) Ammonia
(B) Nitrogen
(C) Oxygen
(D) Helium
Answer: (A)
Explanation: Ammonia (NH₃) was widely used as a refrigerant in early refrigeration systems due to its favorable thermodynamic properties.
21. The coordination number of Zn²⁺ in ZnS (zinc blende) is –
(A) 4
(B) 6
(C) 8
(D) 12
Answer: (A)
Explanation: In the zinc blende structure, each Zn²⁺ ion is tetrahedrally coordinated by four S²⁻ ions, giving a coordination number of 4.
22. Which of the following is a natural polymer?
(A) Nylon
(B) Polythene
(C) Starch
(D) PVC
Answer: (C)
Explanation: Starch is a natural polysaccharide, while nylon, polythene, and PVC are synthetic polymers.
23. The unit of cell constant in conductivity measurements is –
(A) S/m
(B) m⁻¹
(C) S·m²/mol
(D) Ohm·m
Answer: (B)
Explanation: The cell constant (l/A) has units of m⁻¹, as it is the ratio of electrode separation (m) to area (m²).
24. The compound responsible for the yellow color in fireworks is –
(A) Sodium chloride
(B) Barium chloride
(C) Strontium nitrate
(D) Copper sulfate
Answer: (A)
Explanation: Sodium chloride produces a yellow flame in fireworks due to the emission spectrum of sodium ions.
25. The number of sigma bonds in benzene (C₆H₆) is –
(A) 6
(B) 9
(C) 12
(D) 15
Answer: (C)
Explanation: Benzene has 6 C-C single bonds (6 sigma), 6 C-H single bonds (6 sigma), and 3 C=C double bonds (3 sigma + 3 pi). Total sigma bonds = 6 + 6 = 12.
26. Which of the following is a strong acid?
(A) HNO₃
(B) H₃PO₄
(C) CH₃COOH
(D) H₂CO₃
Answer: (A)
Explanation: Nitric acid (HNO₃) is a strong acid, fully dissociating in water, unlike the weak acids H₃PO₄, CH₃COOH, and H₂CO₃.
27. The color of fluorine gas is –
(A) Colorless
(B) Pale yellow
(C) Green
(D) Red
Answer: (B)
Explanation: Fluorine gas (F₂) is pale yellow due to its electronic transitions, though it is rarely observed due to its high reactivity.
28. The process of converting a liquid to a solid is called –
(A) Sublimation
(B) Freezing
(C) Evaporation
(D) Deposition
Answer: (B)
Explanation: Freezing is the phase transition from liquid to solid, such as water forming ice.
29. The most abundant metal in Earth’s crust is –
(A) Iron
(B) Aluminum
(C) Silicon
(D) Magnesium
Answer: (B)
Explanation: Aluminum is the most abundant metal in Earth’s crust (~8%), followed by iron, calcium, and magnesium.
30. The element used in smoke bombs is –
(A) Phosphorus
(B) Sulfur
(C) Potassium chlorate
(D) Magnesium
Answer: (C)
Explanation: Potassium chlorate (KClO₃) is used in smoke bombs, reacting to produce smoke and oxygen.
31. The functional group in aldehydes is –
(A) -OH
(B) -CHO
(C) -COOH
(D) -COOR
Answer: (B)
Explanation: Aldehydes are characterized by the -CHO group, with a carbon double-bonded to oxygen and single-bonded to hydrogen.
32. The rate of diffusion 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 diffusion is proportional to 1/√M, where M is the molecular weight.
33. Which of the following is an emulsion?
(A) Milk
(B) Sugar syrup
(C) Saltwater
(D) Vinegar
Answer: (A)
Explanation: Milk is an emulsion, a colloid with liquid fat droplets dispersed in water. Sugar syrup, saltwater, and vinegar are true solutions.
34. The oxidation number of chlorine in ClO₂ is –
(A) +1
(B) +3
(C) +4
(D) +5
Answer: (C)
Explanation: In ClO₂, O = -2. Let Cl = x. Then, x + 2(-2) = 0 → x – 4 = 0 → x = +4.
35. The allotrope of carbon used in electrodes is –
(A) Diamond
(B) Graphite
(C) Fullerene
(D) Charcoal
Answer: (B)
Explanation: Graphite is used in electrodes due to its high electrical conductivity from delocalized π-electrons in its layered structure.
36. The SI unit of electric dipole moment is –
(A) Coulomb-meter
(B) Ampere-meter
(C) Volt-meter
(D) Ohm-meter
Answer: (A)
Explanation: Electric dipole moment is charge × distance, with SI unit coulomb-meter (C·m).
37. The compound used as a preservative in food is –
(A) Sodium chloride
(B) Sodium benzoate
(C) Ethanol
(D) Chloroform
Answer: (B)
Explanation: Sodium benzoate (C₆H₅COONa) is used as a food preservative to inhibit microbial growth.
38. The reaction Zn + CuSO₄ → ZnSO₄ + Cu is an example of –
(A) Combination
(B) Decomposition
(C) Displacement
(D) Double displacement
Answer: (C)
Explanation: This is a displacement reaction, where zinc displaces copper from copper sulfate due to its higher reactivity.
39. The element with atomic number 18 belongs to –
(A) Alkali metals
(B) Halogens
(C) Noble gases
(D) Alkaline earth metals
Answer: (C)
Explanation: Atomic number 18 corresponds to argon, in group 18 (noble gases).
40. The solubility of a solid in a liquid generally increases with –
(A) Decreasing temperature
(B) Increasing temperature
(C) Decreasing pressure
(D) Increasing volume
Answer: (B)
Explanation: For most solids, solubility in liquids increases with temperature due to enhanced kinetic energy breaking solute-solvent interactions.
41. The compound responsible for the smell of rancid oil is –
(A) Acetic acid
(B) Butyric acid
(C) Formaldehyde
(D) Acetaldehyde
Answer: (B)
Explanation: Butyric acid, formed from the hydrolysis of fats, gives rancid oil its unpleasant odor.
42. The crystal structure of cesium chloride (CsCl) is –
(A) Face-centered cubic
(B) Body-centered cubic
(C) Hexagonal
(D) Orthorhombic
Answer: (B)
Explanation: CsCl has a body-centered cubic structure, with each Cs⁺ ion surrounded by eight Cl⁻ ions.
43. The gas used in fluorescent tubes is –
(A) Helium
(B) Neon
(C) Argon
(D) Mercury vapor
Answer: (D)
Explanation: Fluorescent tubes use mercury vapor, which emits UV light when excited, causing the phosphor coating to fluoresce.
44. The common name for ethanedioic acid is –
(A) Formic acid
(B) Acetic acid
(C) Oxalic acid
(D) Propionic acid
Answer: (C)
Explanation: Ethanedioic acid (HOOC-COOH) is commonly known as oxalic acid, found in some plants.
45. The phenomenon of light scattering by colloidal particles is called –
(A) Tyndall effect
(B) Brownian motion
(C) Electrophoresis
(D) Coagulation
Answer: (A)
Explanation: The Tyndall effect is the scattering of light by colloidal particles, visible as a beam in solutions like milk.
46. The element used in thermocouples is –
(A) Copper
(B) Chromel
(C) Iron
(D) Zinc
Answer: (B)
Explanation: Chromel (a nickel-chromium alloy) is commonly used in thermocouples with alumel to measure temperature via the Seebeck effect.
47. The formula of slaked lime is –
(A) CaCO₃
(B) CaO
(C) Ca(OH)₂
(D) CaSO₄
Answer: (C)
Explanation: Slaked lime is calcium hydroxide (Ca(OH)₂), formed by reacting quicklime (CaO) with water.
48. The oxidation number of sulfur in S₂O₃²⁻ is –
(A) +2
(B) +4
(C) +6
(D) +3
Answer: (A)
Explanation: In S₂O₃²⁻ (thiosulfate), O = -2. Let S = x. Then, 2x + 3(-2) = -2 → 2x – 6 = -2 → 2x = 4 → x = +2 (average oxidation state).
49. Which of the following is a redox reaction?
(A) NaCl + AgNO₃ → AgCl + NaNO₃
(B) 2H₂ + O₂ → 2H₂O
(C) HCl + NaOH → NaCl + H₂O
(D) CaCO₃ → CaO + CO₂
Answer: (B)
Explanation: In 2H₂ + O₂ → 2H₂O, hydrogen is oxidized (0 to +1) and oxygen is reduced (0 to -2), making it a redox reaction. The others are not redox processes.
50. The IUPAC name of CH₃CH₂COCH₃ is –
(A) Propanone
(B) Butanone
(C) Ethanal
(D) Pentanone
Answer: (B)
Explanation: CH₃CH₂COCH₃ has four carbon atoms and a ketone group, so its IUPAC name is butanone.