1. The hybridization of the central atom in ICl₄⁻ is –
(A) sp³
(B) sp³d
(C) sp³d²
(D) dsp²
Answer: (C)
Explanation: Iodine in ICl₄⁻ has four bonding pairs and two lone pairs, requiring six hybrid orbitals. This is achieved through sp³d² hybridization, resulting in a square planar shape per VSEPR theory.
2. Which gas is used in the production of soda ash?
(A) Carbon dioxide
(B) Ammonia
(C) Nitrogen
(D) Oxygen
Answer: (A)
Explanation: Soda ash (Na₂CO₃) is produced via the Solvay process, where carbon dioxide reacts with sodium chloride and ammonia to form sodium bicarbonate, which is then heated to produce soda ash.
3. The bond angle in methane (CH₄) is –
(A) 90°
(B) 104.5°
(C) 109.5°
(D) 120°
Answer: (C)
Explanation: Methane has a tetrahedral shape with four bonding pairs and no lone pairs, resulting in a bond angle of 109.5°, as predicted by VSEPR theory.
4. The primary source of nitrogen oxides (NOx) in the atmosphere is –
(A) Volcanic eruptions
(B) Lightning
(C) Industrial emissions
(D) Photosynthesis
Answer: (C)
Explanation: Nitrogen oxides (NO and NO₂) are primarily produced from industrial activities, vehicle exhausts, and power plants, contributing to air pollution and smog.
5. Which of the following is a neutral ligand?
(A) Cl⁻
(B) NH₃
(C) CN⁻
(D) OH⁻
Answer: (B)
Explanation: A neutral ligand has no charge. Ammonia (NH₃) is neutral, while Cl⁻, CN⁻, and OH⁻ are negatively charged ligands.
6. The rate of a first-order reaction is proportional to –
(A) [Reactant]²
(B) [Reactant]
(C) 1/[Reactant]
(D) [Catalyst]
Answer: (B)
Explanation: For a first-order reaction, the rate law is rate = k[A], so the rate is directly proportional to the concentration of the reactant.
7. The element with the smallest atomic radius in group 17 is –
(A) Fluorine
(B) Chlorine
(C) Bromine
(D) Iodine
Answer: (A)
Explanation: Atomic radius decreases across a period and increases down a group. Fluorine, at the top of group 17 (halogens), has the smallest atomic radius.
8. The shape of the SO₄²⁻ ion is –
(A) Trigonal planar
(B) Tetrahedral
(C) Square planar
(D) Linear
Answer: (B)
Explanation: The sulfate ion (SO₄²⁻) has four bonding pairs and no lone pairs around sulfur, resulting in a tetrahedral shape with 109.5° bond angles.
9. The catalyst used in the cracking of hydrocarbons is –
(A) Platinum
(B) Zeolite
(C) Iron
(D) Nickel
Answer: (B)
Explanation: Zeolites, due to their porous structure, are used as catalysts in the catalytic cracking of hydrocarbons to produce gasoline and other fuels.
10. Which of the following ions is paramagnetic?
(A) Mg²⁺
(B) Sc³⁺
(C) Ni²⁺
(D) Ca²⁺
Answer: (C)
Explanation: Paramagnetic ions have unpaired electrons. Ni²⁺ ([Ar]3d⁸) has two unpaired electrons, while Mg²⁺, Sc³⁺, and Ca²⁺ have fully paired or empty d-orbitals.
11. The functional group in alkynes is –
(A) -C≡C-
(B) -C=C-
(C) -OH
(D) -NH₂
Answer: (A)
Explanation: Alkynes are characterized by a carbon-carbon triple bond (-C≡C-), which includes one sigma and two pi bonds.
12. The pH of a 0.01 M solution of a weak base (Kb = 10⁻⁶) is –
(A) 4
(B) 6
(C) 8
(D) 10
Answer: (C)
Explanation: For a weak base, [OH⁻] = √(Kb × [B]) = √(10⁻⁶ × 0.01) = √10⁻⁸ = 10⁻⁴ M. pOH = -log(10⁻⁴) = 4. pH = 14 – pOH = 14 – 4 = 10.
13. The oxidation state of chromium in Cr₂O₇²⁻ is –
(A) +3
(B) +4
(C) +6
(D) +7
Answer: (C)
Explanation: In Cr₂O₇²⁻, O = -2. Let Cr = x. Then, 2x + 7(-2) = -2 → 2x – 14 = -2 → 2x = 12 → x = +6.
14. Which of the following is a primary amine?
(A) CH₃NH₂
(B) (CH₃)₂NH
(C) (CH₃)₃N
(D) C₆H₅NHCH₃
Answer: (A)
Explanation: A primary amine has one alkyl group attached to nitrogen. CH₃NH₂ (methylamine) is a primary amine, while the others are secondary or tertiary.
15. Gibbs free energy (ΔG) determines –
(A) Heat of reaction
(B) Spontaneity of a reaction
(C) Entropy change
(D) Work done
Answer: (B)
Explanation: Gibbs free energy (ΔG = ΔH – TΔS) determines whether a reaction is spontaneous (ΔG < 0), non-spontaneous (ΔG > 0), or at equilibrium (ΔG = 0).
16. The metal used in thermite welding is –
(A) Iron
(B) Aluminum
(C) Copper
(D) Zinc
Answer: (B)
Explanation: Aluminum powder is used in thermite welding, reacting with iron oxide to produce molten iron and aluminum oxide, generating intense heat.
17. The monomer of bakelite is –
(A) Phenol and formaldehyde
(B) Ethylene
(C) Styrene
(D) Vinyl chloride
Answer: (A)
Explanation: Bakelite is a thermosetting polymer formed by the condensation of phenol and formaldehyde.
18. The half-life of a first-order reaction is –
(A) Independent of rate constant
(B) Proportional to initial concentration
(C) Inversely proportional to rate constant
(D) Proportional to temperature
Answer: (C)
Explanation: For a first-order reaction, t₁/₂ = ln(2)/k, which is inversely proportional to the rate constant (k) and independent of initial concentration.
19. Which of the following is an acidic salt?
(A) Na₂SO₄
(B) NH₄Cl
(C) KNO₃
(D) Na₂CO₃
Answer: (B)
Explanation: NH₄Cl is an acidic salt, formed from a weak base (NH₃) and a strong acid (HCl), producing H⁺ in solution. The others are neutral or basic salts.
20. The gas used in diving cylinders is –
(A) Oxygen
(B) Helium
(C) Nitrogen
(D) Helium-oxygen mixture
Answer: (D)
Explanation: A helium-oxygen mixture (heliox) is used in diving cylinders to reduce nitrogen narcosis and oxygen toxicity at high pressures.
21. The coordination number of Ca²⁺ in CaF₂ is –
(A) 4
(B) 6
(C) 8
(D) 12
Answer: (C)
Explanation: In the fluorite (CaF₂) structure, each Ca²⁺ ion is surrounded by eight F⁻ ions, giving a coordination number of 8.
22. Which of the following is a non-biodegradable polymer?
(A) Polylactic acid
(B) Polythene
(C) Starch
(D) Cellulose
Answer: (B)
Explanation: Polythene (polyethylene) is non-biodegradable, persisting in the environment, unlike polylactic acid, starch, and cellulose, which are biodegradable.
23. The unit of molar conductivity is –
(A) S·m²/mol
(B) S/m
(C) Ohm·m
(D) S·mol/m²
Answer: (A)
Explanation: Molar conductivity (Λm) is specific conductance divided by molarity, with SI unit S·m²/mol.
24. The compound responsible for the red color in fireworks is –
(A) Strontium nitrate
(B) Barium chloride
(C) Copper sulfate
(D) Sodium chloride
Answer: (A)
Explanation: Strontium nitrate produces a red flame in fireworks due to the emission spectrum of strontium ions.
25. The number of pi bonds in ethyne (C₂H₂) is –
(A) 1
(B) 2
(C) 3
(D) 4
Answer: (B)
Explanation: Ethyne (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) NaCl
(B) H₂SO₄
(C) NH₄OH
(D) KOH
Answer: (C)
Explanation: NH₄OH (ammonium hydroxide) is a weak electrolyte, partially dissociating in water, unlike strong electrolytes NaCl, H₂SO₄, and KOH.
27. The color of chlorine gas is –
(A) Colorless
(B) Yellow-green
(C) Red
(D) Blue
Answer: (B)
Explanation: Chlorine gas (Cl₂) has a characteristic yellow-green color due to its electronic transitions.
28. The process of converting a gas to a liquid is called –
(A) Sublimation
(B) Condensation
(C) Evaporation
(D) Deposition
Answer: (B)
Explanation: Condensation is the phase transition from gas to liquid, such as water vapor forming droplets.
29. The fourth most abundant gas in Earth’s atmosphere is –
(A) Oxygen
(B) Nitrogen
(C) Carbon dioxide
(D) Argon
Answer: (C)
Explanation: Carbon dioxide (0.0407%) is the fourth most abundant gas in Earth’s atmosphere, after nitrogen (78%), oxygen (21%), and argon (0.93%).
30. The element used in X-ray tubes is –
(A) Tungsten
(B) Copper
(C) Iron
(D) Aluminum
Answer: (A)
Explanation: Tungsten is used in X-ray tubes due to its high melting point and ability to produce X-rays when bombarded with electrons.
31. The functional group in alkenes is –
(A) -C≡C-
(B) -C=C-
(C) -OH
(D) -NH₂
Answer: (B)
Explanation: Alkenes are characterized by a carbon-carbon double bond (-C=C-), consisting of one sigma and one pi bond.
32. The rate of effusion 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 effusion is inversely proportional to √M, where M is the molecular weight.
33. Which of the following is a colloid?
(A) Sugar syrup
(B) Fog
(C) Saltwater
(D) Vinegar
Answer: (B)
Explanation: Fog is a colloid, with liquid water droplets dispersed in air. Sugar syrup, saltwater, and vinegar are true solutions.
34. The oxidation number of nitrogen in NO₃⁻ is –
(A) +3
(B) +5
(C) +4
(D) +6
Answer: (B)
Explanation: In NO₃⁻, O = -2. Let N = x. Then, x + 3(-2) = -1 → x – 6 = -1 → x = +5.
35. The allotrope of sulfur that is stable at room temperature is –
(A) Rhombic sulfur
(B) Monoclinic sulfur
(C) Plastic sulfur
(D) Amorphous sulfur
Answer: (A)
Explanation: Rhombic sulfur is the most stable allotrope of sulfur at room temperature, with a crystalline structure.
36. The SI unit of pressure is –
(A) Pascal
(B) Bar
(C) Atm
(D) Torr
Answer: (A)
Explanation: The SI unit of pressure is the pascal (Pa), equal to N/m².
37. The compound used as an antiseptic is –
(A) Ethanol
(B) Methanol
(C) Chloroform
(D) Formaldehyde
Answer: (A)
Explanation: Ethanol (C₂H₅OH) is commonly used as an antiseptic due to its ability to kill bacteria and viruses.
38. The reaction 2H₂ + O₂ → 2H₂O is an example of –
(A) Decomposition
(B) Combination
(C) Displacement
(D) Double displacement
Answer: (B)
Explanation: This is a combination reaction, where hydrogen and oxygen combine to form water.
39. The element with atomic number 20 belongs to –
(A) Alkali metals
(B) Halogens
(C) Alkaline earth metals
(D) Noble gases
Answer: (C)
Explanation: Atomic number 20 corresponds to calcium, in group 2 (alkaline earth metals).
40. The solubility of a gas in a liquid increases with –
(A) Decreasing pressure
(B) Increasing temperature
(C) Increasing pressure
(D) Decreasing volume
Answer: (C)
Explanation: According to Henry’s law, the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid, increasing with higher pressure.
41. The compound responsible for the smell of rotten eggs is –
(A) Hydrogen sulfide
(B) Sulfur dioxide
(C) Methane
(D) Ammonia
Answer: (A)
Explanation: Hydrogen sulfide (H₂S) has a characteristic rotten egg odor due to its volatile sulfur content, produced in processes like bacterial decomposition.
42. The crystal structure of zinc blende (ZnS) is –
(A) Body-centered cubic
(B) Face-centered cubic
(C) Hexagonal close-packed
(D) Cubic close-packed
Answer: (B)
Explanation: Zinc blende (ZnS) has a face-centered cubic structure, with Zn²⁺ and S²⁻ ions arranged in a diamond-like lattice.
43. The gas used in incandescent bulbs is –
(A) Helium
(B) Argon
(C) Neon
(D) Krypton
Answer: (B)
Explanation: Argon is used in incandescent bulbs to prevent filament oxidation and prolong bulb life due to its inert nature.
44. The common name for butanoic acid is –
(A) Formic acid
(B) Acetic acid
(C) Propionic acid
(D) Butyric acid
Answer: (D)
Explanation: Butanoic acid (C₃H₇COOH) is commonly known as butyric acid, responsible for the rancid smell in butter.
45. The phenomenon of bending of light due to a change in medium is called –
(A) Diffraction
(B) Refraction
(C) Dispersion
(D) Polarization
Answer: (B)
Explanation: Refraction is the bending of light as it passes from one medium to another with a different refractive index, such as air to glass.
46. The element used in LEDs is –
(A) Silicon
(B) Gallium
(C) Germanium
(D) Arsenic
Answer: (B)
Explanation: Gallium, often in compounds like gallium arsenide or gallium nitride, is used in LEDs due to its semiconductor properties and ability to emit light.
47. The formula of quicklime is –
(A) CaCO₃
(B) CaO
(C) Ca(OH)₂
(D) CaSO₄
Answer: (B)
Explanation: Quicklime is calcium oxide (CaO), produced by heating limestone (CaCO₃) and used in construction and industry.
48. The oxidation number of manganese in MnO₄⁻ is –
(A) +5
(B) +6
(C) +7
(D) +4
Answer: (C)
Explanation: In MnO₄⁻ (permanganate), O = -2. Let Mn = x. Then, x + 4(-2) = -1 → x – 8 = -1 → x = +7.
49. Which of the following is a conjugate acid-base pair?
(A) HCl and NaCl
(B) H₂SO₄ and SO₄²⁻
(C) NH₄⁺ and NH₃
(D) H₂O and OH⁻
Answer: (C)
Explanation: A conjugate acid-base pair differs by one proton (H⁺). NH₄⁺ (acid) donates a proton to form NH₃ (base), making them a conjugate pair.
50. The IUPAC name of CH₃CH₂CHO is –
(A) Methanal
(B) Ethanal
(C) Propanal
(D) Butanal
Answer: (C)
Explanation: CH₃CH₂CHO has three carbon atoms and an aldehyde group, so its IUPAC name is propanal.