1. The hybridization of the central atom in [Ni(H₂O)₆]²⁺ is –
(A) sp³
(B) d²sp³
(C) sp³d²
(D) dsp²
Answer: (C)
Explanation: Nickel in [Ni(H₂O)₆]²⁺ forms six bonds with water ligands in an octahedral geometry, requiring six hybrid orbitals. Ni²⁺ uses sp³d² hybridization for this arrangement.
2. Which gas is used in the production of potassium permanganate?
(A) Oxygen
(B) Chlorine
(C) Carbon dioxide
(D) Nitrogen
Answer: (A)
Explanation: Potassium permanganate (KMnO₄) is produced by oxidizing manganese dioxide (MnO₂) with oxygen in the presence of potassium hydroxide.
3. The bond angle in the PCl₃ molecule is approximately –
(A) 90°
(B) 103°
(C) 109.5°
(D) 120°
Answer: (B)
Explanation: PCl₃ has a trigonal pyramidal shape with three bonding pairs and one lone pair on phosphorus, resulting in a bond angle of ~103° due to lone pair repulsion, per VSEPR theory.
4. The primary source of methane in the atmosphere is –
(A) Volcanic activity
(B) Wetlands and livestock
(C) Industrial emissions
(D) Combustion
Answer: (B)
Explanation: Methane (CH₄), a potent greenhouse gas, is primarily released from wetlands (microbial activity) and livestock (enteric fermentation).
5. Which of the following is a pentadentate ligand?
(A) Diethylenetriamine
(B) EDTA
(C) Triethylenetetramine
(D) Pentamethylenetetramine
Answer: (D)
Explanation: Pentamethylenetetramine is a pentadentate ligand, binding to a metal ion at five nitrogen atoms, unlike diethylenetriamine (tridentate), EDTA (hexadentate), or triethylenetetramine (tetradentate).
6. The equilibrium constant (Kc) of a reaction is affected by –
(A) Concentration of reactants
(B) Temperature
(C) Pressure
(D) Volume
Answer: (B)
Explanation: The equilibrium constant (Kc) depends on temperature, as it affects the Gibbs free energy (ΔG = -RT ln K). Concentration, pressure, and volume affect the position of equilibrium but not Kc.
7. The element with the lowest ionization energy in group 16 is –
(A) Oxygen
(B) Sulfur
(C) Selenium
(D) Polonium
Answer: (D)
Explanation: Ionization energy decreases down a group due to increasing atomic size. Polonium, at the bottom of group 16, has the lowest ionization energy.
8. The shape of the SF₄ molecule is –
(A) Tetrahedral
(B) See-saw
(C) Square planar
(D) Trigonal pyramidal
Answer: (B)
Explanation: SF₄ has four bonding pairs and one lone pair on sulfur, resulting in a see-saw shape from a trigonal bipyramidal electron geometry.
9. The catalyst used in the production of formaldehyde from methanol is –
(A) Silver
(B) Platinum
(C) Nickel
(D) Iron
Answer: (A)
Explanation: Formaldehyde (HCHO) is produced by the catalytic oxidation of methanol (CH₃OH) using silver as a catalyst at high temperatures.
10. Which of the following ions is diamagnetic?
(A) Mn³⁺
(B) Fe²⁺
(C) Ba²⁺
(D) Co³⁺
Answer: (C)
Explanation: Diamagnetic ions have all paired electrons. Ba²⁺ ([Xe]) has no unpaired electrons, while Mn³⁺, Fe²⁺, and Co³⁺ have unpaired d-electrons.
11. The functional group in ketones is –
(A) -COOH
(B) -CHO
(C) -CO-
(D) -OH
Answer: (C)
Explanation: Ketones are characterized by the -CO- group (carbonyl), with the carbon bonded to two alkyl groups.
12. The pOH of a 0.01 M solution of a weak base (Kb = 10⁻⁴) is –
(A) 2
(B) 3
(C) 4
(D) 5
Answer: (B)
Explanation: For a weak base, [OH⁻] = √(Kb × [B]) = √(10⁻⁴ × 0.01) = √10⁻⁶ = 10⁻³ M. pOH = -log(10⁻³) = 3. (pH = 14 – pOH = 11).
13. The oxidation state of iron in [Fe(CN)₆]³⁻ is –
(A) +2
(B) +3
(C) +4
(D) +6
Answer: (B)
Explanation: CN⁻ is a -1 ligand. The complex has a -3 charge. Let Fe = x. Then, x + 6(-1) = -3 → x – 6 = -3 → x = +3.
14. Which of the following is a primary amine?
(A) CH₃NH₂
(B) (CH₃)₂NH
(C) (CH₃)₃N
(D) C₆H₅NH₂
Answer: (A)
Explanation: A primary amine has one alkyl or aryl group attached to nitrogen. CH₃NH₂ (methylamine) is a primary amine.
15. The standard entropy change of a reaction is positive when –
(A) Products are more ordered than reactants
(B) Reactants are more ordered than products
(C) Heat is absorbed
(D) Work is done
Answer: (B)
Explanation: A positive ΔS indicates an increase in disorder, meaning products are less ordered (more random) than reactants.
16. The metal used in the production of brass is –
(A) Zinc
(B) Tin
(C) Aluminum
(D) Both (A) and (B)
Answer: (A)
Explanation: Brass is an alloy of copper and zinc, known for its malleability and corrosion resistance.
17. The monomer of nylon-6 is –
(A) Adipic acid
(B) Caprolactam
(C) Hexamethylenediamine
(D) Terephthalic acid
Answer: (B)
Explanation: Nylon-6 is a polymer of caprolactam, which undergoes ring-opening polymerization to form polyamide chains.
18. The rate of a zero-order reaction is –
(A) Proportional to concentration
(B) Independent of concentration
(C) Inversely proportional to concentration
(D) Proportional to temperature only
Answer: (B)
Explanation: For a zero-order reaction, rate = k, meaning the rate is constant and independent of reactant concentration.
19. Which of the following is a neutral salt?
(A) NaH₂PO₄
(B) NH₄Cl
(C) NaCl
(D) Na₂CO₃
Answer: (C)
Explanation: NaCl, formed from a strong acid (HCl) and a strong base (NaOH), is a neutral salt, producing no H⁺ or OH⁻ in solution.
20. The gas used in sodium-vapor lamps is –
(A) Neon
(B) Sodium vapor
(C) Argon
(D) Helium
Answer: (B)
Explanation: Sodium-vapor lamps use sodium vapor, which emits a characteristic yellow light when electrified.
21. The coordination number of Fe²⁺ in [Fe(CN)₆]⁴⁻ is –
(A) 4
(B) 6
(C) 8
(D) 12
Answer: (B)
Explanation: In [Fe(CN)₆]⁴⁻, Fe²⁺ is coordinated by six cyanide ligands in an octahedral arrangement, giving a coordination number of 6.
22. Which of the following is a biodegradable polymer?
(A) Polyethylene
(B) Polyvinyl chloride
(C) Polyhydroxyalkanoates
(D) Polystyrene
Answer: (C)
Explanation: Polyhydroxyalkanoates (PHA) are biodegradable polymers produced by bacteria, unlike polyethylene, PVC, and polystyrene.
23. The unit of specific conductivity is –
(A) S m⁻¹
(B) S m² mol⁻¹
(C) S m²
(D) S mol⁻¹
Answer: (A)
Explanation: Specific conductivity (κ) measures a material’s ability to conduct electricity, with SI unit S m⁻¹ (siemens per meter).
24. The compound responsible for the yellow color in glass is –
(A) Chromium oxide
(B) Cadmium sulfide
(C) Cobalt oxide
(D) Iron oxide
Answer: (B)
Explanation: Cadmium sulfide (CdS) imparts a yellow color to glass, used in decorative applications.
25. The number of sigma bonds in propyne (C₃H₄) is –
(A) 4
(B) 5
(C) 6
(D) 7
Answer: (C)
Explanation: Propyne (CH₃C≡CH) has one C≡C triple bond (1 sigma + 2 pi), one C-C single bond (1 sigma), and four C-H single bonds (4 sigma). Total sigma bonds = 1 + 1 + 4 = 6.
26. Which of the following is a strong electrolyte?
(A) CH₃COOH
(B) NH₄OH
(C) K₂SO₄
(D) HCN
Answer: (C)
Explanation: K₂SO₄ is a strong electrolyte, fully dissociating in water, unlike weak electrolytes CH₃COOH, NH₄OH, and HCN.
27. The color of calcium chloride flame in a flame test is –
(A) Green
(B) Red
(C) Blue
(D) Yellow
Answer: (B)
Explanation: Calcium ions produce a red flame in a flame test due to electron transitions in the calcium atom.
28. The process of converting a gas to a liquid below its critical temperature is –
(A) Condensation
(B) Liquefaction
(C) Sublimation
(D) Deposition
Answer: (A)
Explanation: Condensation is the process of converting a gas to a liquid below its critical temperature, often by cooling.
29. The second most abundant metal in Earth’s crust is –
(A) Aluminum
(B) Iron
(C) Calcium
(D) Magnesium
Answer: (B)
Explanation: Iron (~5%) is the second most abundant metal in Earth’s crust, after aluminum (~8%).
30. The element used in the production of incendiary bombs is –
(A) Phosphorus
(B) Magnesium
(C) Aluminum
(D) All of the above
Answer: (D)
Explanation: Phosphorus, magnesium, and aluminum are used in incendiary bombs for their ability to burn intensely.
31. The functional group in thiols is –
(A) -SH
(B) -OH
(C) -NH₂
(D) -COOH
Answer: (A)
Explanation: Thiols are characterized by the -SH (sulfhydryl) group, analogous to the -OH group in alcohols.
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 aerosol?
(A) Smoke
(B) Milk
(C) Jelly
(D) Cheese
Answer: (A)
Explanation: Smoke is an aerosol, a colloid with solid particles dispersed in a gas. Milk is an emulsion, jelly and cheese are gels.
34. 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).
35. The allotrope of phosphorus used in matches is –
(A) White phosphorus
(B) Red phosphorus
(C) Black phosphorus
(D) Yellow phosphorus
Answer: (B)
Explanation: Red phosphorus, stable and less reactive, is used in the striking surface of matches, unlike the highly reactive white (or yellow) phosphorus.
36. The SI unit of equivalent conductivity is –
(A) S m² mol⁻¹
(B) S m² equiv⁻¹
(C) S m⁻¹
(D) S mol⁻¹
Answer: (B)
Explanation: Equivalent conductivity is conductivity divided by the normality of the electrolyte, with SI unit S m² equiv⁻¹.
37. The compound used as a preservative is –
(A) Sodium benzoate
(B) Sodium chloride
(C) Ethanol
(D) Chloroform
Answer: (A)
Explanation: Sodium benzoate (C₆H₅COONa) is used as a preservative in food and beverages to inhibit microbial growth.
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 melting point of a substance decreases with –
(A) Increasing pressure
(B) Decreasing pressure
(C) Increasing temperature
(D) Decreasing volume
Answer: (B)
Explanation: For substances where the liquid phase is less dense than the solid (e.g., water), decreasing pressure lowers the melting point, per Le Chatelier’s principle.
41. The compound responsible for the smell of oranges is –
(A) Limonene
(B) Isoamyl acetate
(C) Ethanol
(D) Acetone
Answer: (A)
Explanation: Limonene, a terpene, is responsible for the citrusy smell of oranges.
42. The crystal structure of diamond is –
(A) Hexagonal
(B) Face-centered cubic
(C) Tetrahedral
(D) Orthorhombic
Answer: (C)
Explanation: Diamond has a tetrahedral crystal structure, with each carbon atom covalently bonded to four others in a 3D network.
43. The gas used in welding torches is –
(A) Acetylene
(B) Helium
(C) Argon
(D) Oxygen
Answer: (A)
Explanation: Acetylene (C₂H₂) is used in oxy-acetylene welding torches for its high flame temperature when burned with oxygen.
44. The common name for hexanoic acid is –
(A) Caproic acid
(B) Valeric acid
(C) Butyric acid
(D) Propionic acid
Answer: (A)
Explanation: Hexanoic acid (CH₃(CH₂)₄COOH) is commonly known as caproic acid, found in animal fats.
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 X-ray tubes is –
(A) Tungsten
(B) Molybdenum
(C) Copper
(D) All of the above
Answer: (D)
Explanation: Tungsten, molybdenum, and copper are used in X-ray tubes for their high melting points and ability to produce X-rays.
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), used in mortar and agriculture.
48. The oxidation number of chlorine in Cl₂O is –
(A) +1
(B) +2
(C) +3
(D) +5
Answer: (A)
Explanation: In Cl₂O, O = -2. Let Cl = x. Then, 2x + (-2) = 0 → 2x – 2 = 0 → x = +1.
49. Which of the following is a conjugate base?
(A) H₃O⁺
(B) NH₄⁺
(C) CH₃COO⁻
(D) H₂SO₄
Answer: (C)
Explanation: A conjugate base is formed by losing a proton. CH₃COO⁻ is the conjugate base of CH₃COOH, unlike the others, which are acids or cations.
50. The IUPAC name of (CH₃)₂CHOH is –
(A) Propan-1-ol
(B) Propan-2-ol
(C) Ethanol
(D) Butan-1-ol
Answer: (B)
Explanation: (CH₃)₂CHOH has three carbon atoms with the hydroxyl group on the second carbon, so its IUPAC name is propan-2-ol.