1. The hybridization of the central atom in [MnCl₆]⁴⁻ is –
(A) sp³
(B) d²sp³
(C) sp³d²
(D) dsp²
Answer: (C)
Explanation: Manganese in [MnCl₆]⁴⁻ forms six bonds with chloride ligands in an octahedral geometry, requiring six hybrid orbitals. Mn³⁺ uses sp³d² hybridization for this arrangement.
2. Which gas is used in the production of phosphoric acid?
(A) Phosphorus trichloride
(B) Sulfur dioxide
(C) Oxygen
(D) Both (B) and (C)
Answer: (C)
Explanation: Phosphoric acid (H₃PO₄) is produced by oxidizing phosphorus with oxygen in the wet process, followed by hydration of P₂O₅.
3. The bond angle in the NH₂⁻ ion is approximately –
(A) 90°
(B) 104.5°
(C) 109.5°
(D) 120°
Answer: (B)
Explanation: NH₂⁻ has a bent shape with two bonding pairs and two lone pairs on nitrogen, resulting in a bond angle of ~104.5°, similar to H₂O, per VSEPR theory.
4. The primary source of ozone in the troposphere is –
(A) Volcanic activity
(B) Photochemical reactions
(C) Industrial emissions
(D) Forest fires
Answer: (B)
Explanation: Tropospheric ozone is primarily formed through photochemical reactions involving nitrogen oxides and volatile organic compounds in the presence of sunlight.
5. Which of the following is a hexadentate ligand?
(A) Ethylenediamine
(B) EDTA
(C) Cyanide
(D) Oxalate
Answer: (B)
Explanation: EDTA (ethylenediaminetetraacetate) is a hexadentate ligand, binding to a metal ion at six sites (two nitrogen and four oxygen atoms).
6. The Arrhenius equation relates the rate constant to –
(A) Concentration
(B) Temperature
(C) Pressure
(D) Volume
Answer: (B)
Explanation: The Arrhenius equation (k = Ae^(-Ea/RT)) relates the rate constant (k) to temperature (T), activation energy (Ea), and the pre-exponential factor (A).
7. The element with the highest ionization energy in group 13 is –
(A) Boron
(B) Aluminum
(C) Gallium
(D) Indium
Answer: (A)
Explanation: Ionization energy decreases down a group due to increasing atomic size. Boron, at the top of group 13, has the highest ionization energy.
8. The shape of the BrF₅ molecule is –
(A) Trigonal bipyramidal
(B) Square pyramidal
(C) Octahedral
(D) T-shaped
Answer: (B)
Explanation: BrF₅ has five bonding pairs and one lone pair on bromine, resulting in a square pyramidal shape from an octahedral electron geometry.
9. The catalyst used in the production of ethanol from ethylene is –
(A) Phosphoric acid
(B) Platinum
(C) Nickel
(D) Iron
Answer: (A)
Explanation: Ethanol (C₂H₅OH) is produced by the hydration of ethylene (C₂H₄) using phosphoric acid as a catalyst in the presence of steam.
10. Which of the following ions is paramagnetic?
(A) Sc³⁺
(B) Ni²⁺
(C) Zn²⁺
(D) Ba²⁺
Answer: (B)
Explanation: Paramagnetic ions have unpaired electrons. Ni²⁺ ([Ar]3d⁸) has two unpaired electrons, while Sc³⁺, Zn²⁺, and Ba²⁺ have fully paired or empty orbitals.
11. The functional group in alcohols is –
(A) -OH
(B) -COOH
(C) -CHO
(D) -NH₂
Answer: (A)
Explanation: Alcohols are characterized by the -OH (hydroxyl) group bonded to a carbon atom.
12. The pH of a 0.01 M solution of a strong base is –
(A) 10
(B) 11
(C) 12
(D) 13
Answer: (C)
Explanation: A strong base fully dissociates. For 0.01 M base, [OH⁻] = 0.01 M = 10⁻² M. pOH = -log(10⁻²) = 2. pH = 14 – pOH = 14 – 2 = 12.
13. The oxidation state of iron in [Fe(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 Fe = x. Then, x + 6(-1) = -4 → x – 6 = -4 → x = +2.
14. Which of the following is a primary alkyl halide?
(A) CH₃Cl
(B) (CH₃)₂CHCl
(C) (CH₃)₃CCl
(D) C₆H₅Cl
Answer: (A)
Explanation: A primary alkyl halide has the halogen on a carbon bonded to one other carbon. CH₃Cl (methyl chloride) is a primary alkyl halide.
15. The second law of thermodynamics states that –
(A) Energy is conserved
(B) Entropy of an isolated system increases
(C) Heat flows from hot to cold
(D) Work equals heat
Answer: (B)
Explanation: The second law states that the entropy of an isolated system increases for spontaneous processes, indicating increasing disorder.
16. The metal used in the production of duralumin is –
(A) Aluminum
(B) Copper
(C) Magnesium
(D) All of the above
Answer: (D)
Explanation: Duralumin is an alloy of aluminum, copper, magnesium, and sometimes manganese, used in aerospace for its strength.
17. The monomer of nylon-6,6 is –
(A) Caprolactam
(B) Adipic acid and hexamethylenediamine
(C) Terephthalic acid
(D) Styrene
Answer: (B)
Explanation: Nylon-6,6 is a polyamide formed from adipic acid and hexamethylenediamine through condensation polymerization.
18. The rate of a third-order reaction is proportional to –
(A) [Reactant]
(B) [Reactant]²
(C) [Reactant]³
(D) 1/[Reactant]
Answer: (C)
Explanation: For a third-order reaction, rate = k[A]³ or k[A]²[B], so the rate is proportional to the cube of the reactant concentration or a combination of concentrations.
19. Which of the following is a neutral oxide?
(A) CO
(B) SO₂
(C) NO₂
(D) P₂O₅
Answer: (A)
Explanation: Carbon monoxide (CO) is a neutral oxide, as it does not react with water to form an acid or base, unlike SO₂, NO₂, and P₂O₅, which are acidic.
20. The gas used in neon signs is –
(A) Neon
(B) Argon
(C) Krypton
(D) Helium
Answer: (A)
Explanation: Neon signs use neon gas, which emits a red-orange glow when electrified, though other gases like argon are used for different colors.
21. The coordination number of Cs⁺ in CsCl is –
(A) 4
(B) 6
(C) 8
(D) 12
Answer: (C)
Explanation: In the CsCl (body-centered cubic) structure, each Cs⁺ ion is surrounded by eight Cl⁻ ions, giving a coordination number of 8.
22. Which of the following is a synthetic polymer?
(A) Cellulose
(B) Polypropylene
(C) Starch
(D) Proteins
Answer: (B)
Explanation: Polypropylene is a synthetic polymer, used in plastics, while cellulose, starch, and proteins are natural polymers.
23. The unit of specific heat capacity is –
(A) J/kg·K
(B) J/mol·K
(C) J/m²
(D) J/K
Answer: (A)
Explanation: Specific heat capacity is the heat required to raise 1 kg of a substance by 1 K, with SI unit J/kg·K.
24. The compound responsible for the purple color in glass is –
(A) Manganese dioxide
(B) Cobalt oxide
(C) Iron oxide
(D) Chromium oxide
Answer: (A)
Explanation: Manganese dioxide (MnO₂) imparts a purple or amethyst color to glass, used in decorative applications.
25. The number of pi bonds in butadiene (C₄H₆) is –
(A) 1
(B) 2
(C) 3
(D) 4
Answer: (B)
Explanation: Butadiene (CH₂=CH-CH=CH₂) has two C=C double bonds, each with one sigma and one pi bond. Total pi bonds = 2.
26. Which of the following is a weak electrolyte?
(A) NaCl
(B) H₂SO₄
(C) NH₃
(D) KOH
Answer: (C)
Explanation: Ammonia (NH₃) is a weak electrolyte, partially dissociating in water, unlike strong electrolytes NaCl, H₂SO₄, and KOH.
27. The color of potassium chloride flame in a flame test is –
(A) Violet
(B) Green
(C) Blue
(D) Yellow
Answer: (A)
Explanation: Potassium ions produce a violet flame in a flame test due to electron transitions in the potassium atom.
28. The process of converting a liquid to a gas below its boiling point is –
(A) Sublimation
(B) Evaporation
(C) Condensation
(D) Deposition
Answer: (B)
Explanation: Evaporation is the process where a liquid turns into a gas below its boiling point, driven by surface molecule escape.
29. The most abundant element in Earth’s crust is –
(A) Oxygen
(B) Silicon
(C) Aluminum
(D) Iron
Answer: (A)
Explanation: Oxygen (~46%) is the most abundant element in Earth’s crust, primarily in silicates and oxides.
30. The element used in the production of flash powders is –
(A) Magnesium
(B) Aluminum
(C) Potassium
(D) All of the above
Answer: (D)
Explanation: Magnesium, aluminum, and potassium are used in flash powders for their bright, rapid combustion in photography and pyrotechnics.
31. The functional group in anhydrides is –
(A) -CO-O-CO-
(B) -COOH
(C) -CHO
(D) -OH
Answer: (A)
Explanation: Anhydrides are characterized by the -CO-O-CO- group, formed by the condensation of two carboxylic acid molecules.
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 a foam?
(A) Whipped cream
(B) Milk
(C) Paint
(D) Jelly
Answer: (A)
Explanation: Whipped cream is a foam, a colloid with gas bubbles dispersed in a liquid. Milk is an emulsion, paint is a sol, and jelly is a gel.
34. The oxidation number of chlorine in ClO₂⁻ is –
(A) +1
(B) +3
(C) +5
(D) +7
Answer: (B)
Explanation: In ClO₂⁻ (chlorite), O = -2. Let Cl = x. Then, x + 2(-2) = -1 → x – 4 = -1 → x = +3.
35. The allotrope of phosphorus that is most reactive is –
(A) White phosphorus
(B) Red phosphorus
(C) Black phosphorus
(D) Violet phosphorus
Answer: (A)
Explanation: White phosphorus, with a tetrahedral P₄ structure, is highly reactive due to its strained bonds, unlike red, black, or violet phosphorus.
36. The SI unit of viscosity is –
(A) Pa·s
(B) N/m
(C) J/m²
(D) kg/m
Answer: (A)
Explanation: Viscosity, the resistance to flow, has the SI unit pascal-second (Pa·s).
37. The compound used as a disinfectant in water treatment is –
(A) Sodium chloride
(B) Chlorine
(C) Ethanol
(D) Formaldehyde
Answer: (B)
Explanation: Chlorine is used as a disinfectant in water treatment to kill pathogens, often as Cl₂ or hypochlorite.
38. The reaction 2H₂O₂ → 2H₂O + O₂ is an example of –
(A) Combination
(B) Decomposition
(C) Displacement
(D) Double displacement
Answer: (B)
Explanation: This is a decomposition reaction, where hydrogen peroxide breaks down into water and oxygen, often catalyzed by manganese dioxide.
39. The element with atomic number 19 belongs to –
(A) Alkali metals
(B) Halogens
(C) Noble gases
(D) Alkaline earth metals
Answer: (A)
Explanation: Atomic number 19 corresponds to potassium, in group 1 (alkali metals).
40. The freezing point of a solution is –
(A) Higher than the pure solvent
(B) Lower than the pure solvent
(C) Equal to the pure solvent
(D) Independent of solute
Answer: (B)
Explanation: The freezing point of a solution is lower than that of the pure solvent due to freezing point depression, a colligative property.
41. The compound responsible for the smell of almonds is –
(A) Benzaldehyde
(B) Acetone
(C) Ethanol
(D) Ethyl acetate
Answer: (A)
Explanation: Benzaldehyde (C₆H₅CHO) is responsible for the almond-like odor, used in flavorings.
42. The crystal structure of sodium chloride (NaCl) is –
(A) Hexagonal
(B) Face-centered cubic
(C) Body-centered cubic
(D) Orthorhombic
Answer: (B)
Explanation: NaCl has a face-centered cubic (rock salt) structure, with alternating Na⁺ and Cl⁻ ions.
43. The gas used in balloons for meteorological studies is –
(A) Helium
(B) Hydrogen
(C) Neon
(D) Argon
Answer: (A)
Explanation: Helium is used in meteorological balloons for its low density and safety compared to hydrogen.
44. The common name for methanoic acid is –
(A) Formic acid
(B) Acetic acid
(C) Propionic acid
(D) Butyric acid
Answer: (A)
Explanation: Methanoic acid (HCOOH) is commonly known as formic acid, found in ant venom.
45. The phenomenon of adsorption of gases on solid surfaces is studied in –
(A) Surface chemistry
(B) Electrochemistry
(C) Thermodynamics
(D) Quantum chemistry
Answer: (A)
Explanation: Adsorption, the adhesion of gas molecules to a solid surface, is a key topic in surface chemistry.
46. The element used in fluorescent lamps is –
(A) Mercury
(B) Neon
(C) Argon
(D) All of the above
Answer: (D)
Explanation: Fluorescent lamps use mercury vapor for UV emission, with neon or argon as starter gases to enhance efficiency.
47. The formula of plaster of Paris is –
(A) CaSO₄
(B) CaSO₄·½H₂O
(C) CaSO₄·2H₂O
(D) Ca(OH)₂
Answer: (B)
Explanation: Plaster of Paris is calcium sulfate hemihydrate (CaSO₄·½H₂O), used in casts and molds.
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 a conjugate acid-base pair?
(A) HCl and NaCl
(B) NH₃ and NH₄⁺
(C) H₂O and OH⁻
(D) H₂SO₄ and SO₄²⁻
Answer: (B)
Explanation: A conjugate acid-base pair differs by one proton. NH₃ (base) and NH₄⁺ (conjugate acid) form such a pair.
50. The IUPAC name of CH₃COCH₃ is –
(A) Propanone
(B) Ethanone
(C) Butanone
(D) Methanone
Answer: (A)
Explanation: CH₃COCH₃ has three carbon atoms with a ketone group, so its IUPAC name is propanone.