1. The hybridization of the central atom in [CoF₆]³⁻ is –
(A) sp³
(B) dsp²
(C) sp³d²
(D) d²sp³
Answer: (C)
Explanation: Cobalt in [CoF₆]³⁻ forms six bonds with fluoride ligands in an octahedral geometry, requiring six hybrid orbitals. Co³⁺ uses sp³d² hybridization for this arrangement.
2. Which gas is used in the production of soda ash?
(A) Carbon dioxide
(B) Nitrogen
(C) Oxygen
(D) Ammonia
Answer: (A)
Explanation: Soda ash (Na₂CO₃) is produced via the Solvay process, where carbon dioxide (CO₂) reacts with ammonia and sodium chloride to form sodium bicarbonate, which is then heated.
3. The bond angle in the H₂O molecule is approximately –
(A) 90°
(B) 104.5°
(C) 109.5°
(D) 120°
Answer: (B)
Explanation: H₂O has a bent shape with two bonding pairs and two lone pairs on oxygen, resulting in a bond angle of ~104.5° due to lone pair repulsion, per VSEPR theory.
4. The primary source of carbon dioxide in the atmosphere is –
(A) Photosynthesis
(B) Respiration and combustion
(C) Volcanic eruptions only
(D) Ocean evaporation
Answer: (B)
Explanation: Carbon dioxide (CO₂) is primarily released through respiration (biological) and combustion (fossil fuels), contributing to the greenhouse effect.
5. Which of the following is a monodentate ligand?
(A) Oxalate
(B) Ethylenediamine
(C) Fluoride
(D) EDTA
Answer: (C)
Explanation: Fluoride (F⁻) is a monodentate ligand, binding to a metal ion at one site, unlike oxalate, ethylenediamine (bidentate), and EDTA (hexadentate).
6. The order of a reaction can be –
(A) Zero or positive only
(B) Positive or negative
(C) Integer or fractional
(D) Both (B) and (C)
Answer: (D)
Explanation: The order of a reaction can be zero, positive, negative (e.g., in inhibition), or fractional, depending on the rate law derived experimentally.
7. The element with the lowest electronegativity in group 14 is –
(A) Carbon
(B) Silicon
(C) Tin
(D) Lead
Answer: (D)
Explanation: Electronegativity decreases down a group due to increasing atomic size. Lead, at the bottom of group 14, has the lowest electronegativity.
8. The shape of the ClF₅ molecule is –
(A) Trigonal bipyramidal
(B) Square pyramidal
(C) Octahedral
(D) T-shaped
Answer: (B)
Explanation: ClF₅ has five bonding pairs and one lone pair on chlorine, resulting in a square pyramidal shape from an octahedral electron geometry.
9. The catalyst used in the production of polyethylene terephthalate (PET) is –
(A) Antimony trioxide
(B) Platinum
(C) Nickel
(D) Iron
Answer: (A)
Explanation: Antimony trioxide is commonly used as a catalyst in the polymerization of ethylene glycol and terephthalic acid to produce PET.
10. Which of the following ions is diamagnetic?
(A) Ni²⁺
(B) Cu²⁺
(C) Mg²⁺
(D) Fe³⁺
Answer: (C)
Explanation: Diamagnetic ions have all paired electrons. Mg²⁺ ([Ne]) has no unpaired electrons, while Ni²⁺, Cu²⁺, and Fe³⁺ have unpaired d-electrons.
11. The functional group in alkenes is –
(A) C=C
(B) C≡C
(C) -OH
(D) -COOH
Answer: (A)
Explanation: Alkenes are characterized by a carbon-carbon double bond (C=C), which includes one sigma and one pi bond.
12. The pOH of a 0.001 M solution of a strong base is –
(A) 2
(B) 3
(C) 4
(D) 5
Answer: (B)
Explanation: A strong base fully dissociates. For 0.001 M base, [OH⁻] = 0.001 M = 10⁻³ M. pOH = -log(10⁻³) = 3. (pH = 14 – pOH = 11).
13. The oxidation state of chromium in [Cr(NH₃)₆]³⁺ is –
(A) +2
(B) +3
(C) +4
(D) +6
Answer: (B)
Explanation: NH₃ is a neutral ligand. The complex has a +3 charge. Let Cr = x. Then, x + 6(0) = +3 → x = +3.
14. Which of the following is a secondary alcohol?
(A) CH₃CH₂OH
(B) (CH₃)₂CHOH
(C) (CH₃)₃COH
(D) C₆H₅CH₂OH
Answer: (B)
Explanation: A secondary alcohol has the -OH group on a carbon bonded to two other carbons. (CH₃)₂CHOH (isopropanol) is a secondary alcohol.
15. The Gibbs free energy change determines –
(A) Heat absorbed
(B) Work done
(C) Spontaneity of a reaction
(D) Entropy change
Answer: (C)
Explanation: Gibbs free energy change (ΔG) determines the spontaneity of a reaction: ΔG < 0 indicates a spontaneous reaction at constant temperature and pressure.
16. The metal used in the production of stainless steel is –
(A) Chromium
(B) Zinc
(C) Tin
(D) Aluminum
Answer: (A)
Explanation: Chromium is added to steel to form stainless steel, enhancing corrosion resistance through a passive oxide layer.
17. The monomer of polystyrene is –
(A) Ethylene
(B) Styrene
(C) Vinyl chloride
(D) Tetrafluoroethylene
Answer: (B)
Explanation: Polystyrene is a polymer of styrene (C₆H₅CH=CH₂), used in packaging and insulation.
18. The half-life of a second-order reaction depends on –
(A) Rate constant only
(B) Initial concentration
(C) Temperature only
(D) Catalyst
Answer: (B)
Explanation: For a second-order reaction, t₁/₂ = 1/(k[A]₀), which depends on the initial concentration ([A]₀) and the rate constant (k).
19. Which of the following is an acidic oxide?
(A) Na₂O
(B) MgO
(C) SO₂
(D) CaO
Answer: (C)
Explanation: SO₂ reacts with water to form sulfurous acid (H₂SO₃), making it an acidic oxide. Na₂O, MgO, and CaO are basic oxides.
20. The gas used in incandescent bulbs is –
(A) Argon
(B) Neon
(C) Helium
(D) Krypton
Answer: (A)
Explanation: Argon is used in incandescent bulbs to prevent filament oxidation and prolong bulb life.
21. The coordination number of Zn²⁺ in zinc blende (ZnS) 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 synthetic polymer?
(A) Starch
(B) Cellulose
(C) Polypropylene
(D) Proteins
Answer: (C)
Explanation: Polypropylene is a synthetic polymer, while starch, cellulose, and proteins are natural polymers.
23. The unit of molar heat capacity is –
(A) J/mol·K
(B) J/kg·K
(C) J/m³·K
(D) J/K
Answer: (A)
Explanation: Molar heat capacity is the heat required to raise 1 mole of a substance by 1 K, with SI unit J/mol·K.
24. The compound responsible for the red color in fireworks is –
(A) Strontium nitrate
(B) Barium chloride
(C) Copper chloride
(D) Potassium chloride
Answer: (A)
Explanation: Strontium nitrate produces a red flame in fireworks due to the emission spectrum of strontium ions.
25. The number of sigma bonds in ethyne (C₂H₂) is –
(A) 2
(B) 3
(C) 4
(D) 5
Answer: (B)
Explanation: Ethyne (HC≡CH) has one C≡C triple bond (1 sigma + 2 pi) and two C-H single bonds (2 sigma). Total sigma bonds = 1 + 2 = 3.
26. Which of the following is a strong acid?
(A) HF
(B) HNO₃
(C) H₃PO₄
(D) CH₃COOH
Answer: (B)
Explanation: Nitric acid (HNO₃) is a strong acid, fully dissociating in water, unlike HF, H₃PO₄, and CH₃COOH, which are weak acids.
27. The color of barium chloride flame in a flame test is –
(A) Green
(B) Yellow
(C) Blue
(D) Red
Answer: (A)
Explanation: Barium ions produce a green flame in a flame test due to electron transitions in the barium atom.
28. The process of converting a liquid to a gas at its boiling point is –
(A) Sublimation
(B) Evaporation
(C) Boiling
(D) Condensation
Answer: (C)
Explanation: Boiling is the process where a liquid turns into a gas at its boiling point, with bubble formation throughout the liquid.
29. The second most abundant gas in Earth’s atmosphere is –
(A) Nitrogen
(B) Oxygen
(C) Carbon dioxide
(D) Argon
Answer: (B)
Explanation: Oxygen (~21%) is the second most abundant gas in Earth’s atmosphere, after nitrogen (~78%).
30. The element used in the production of flares is –
(A) Magnesium
(B) Sodium
(C) Strontium
(D) All of the above
Answer: (D)
Explanation: Magnesium (bright white light), sodium (yellow), and strontium (red) are used in flares for illumination and signaling.
31. The functional group in alkynes is –
(A) C=C
(B) C≡C
(C) -OH
(D) -COOH
Answer: (B)
Explanation: Alkynes are characterized by a carbon-carbon triple bond (C≡C), consisting of one sigma and two pi bonds.
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 foam?
(A) Shaving cream
(B) Milk
(C) Paint
(D) Sugar syrup
Answer: (A)
Explanation: Shaving cream is a foam, a colloid with gas bubbles dispersed in a liquid. Milk is an emulsion, paint is a sol, and sugar syrup is a solution.
34. The oxidation number of nitrogen in NH₃ is –
(A) -3
(B) +3
(C) 0
(D) +1
Answer: (A)
Explanation: In NH₃, H = +1. Let N = x. Then, x + 3(+1) = 0 → x + 3 = 0 → x = -3.
35. The allotrope of sulfur that is crystalline and 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 crystalline allotrope of sulfur at room temperature.
36. The SI unit of dipole moment is –
(A) Coulomb-meter
(B) Ampere-meter
(C) Volt-meter
(D) Ohm-meter
Answer: (A)
Explanation: Dipole moment is charge × distance, with SI unit coulomb-meter (C·m).
37. The compound used as a bleaching agent is –
(A) Sodium chloride
(B) Hydrogen peroxide
(C) Ethanol
(D) Chloroform
Answer: (B)
Explanation: Hydrogen peroxide (H₂O₂) is used as a bleaching agent due to its oxidizing properties.
38. The reaction CaCO₃ → CaO + CO₂ is an example of –
(A) Combination
(B) Decomposition
(C) Displacement
(D) Double displacement
Answer: (B)
Explanation: This is a decomposition reaction, where calcium carbonate breaks down into calcium oxide and carbon dioxide upon heating.
39. The element with atomic number 20 belongs to –
(A) Alkali metals
(B) Halogens
(C) Noble gases
(D) Alkaline earth metals
Answer: (D)
Explanation: Atomic number 20 corresponds to calcium, in group 2 (alkaline earth metals).
40. The boiling point of a liquid decreases with –
(A) Increasing pressure
(B) Decreasing pressure
(C) Increasing temperature
(D) Decreasing volume
Answer: (B)
Explanation: Decreasing pressure lowers the boiling point of a liquid, as less energy is required for molecules to enter the gas phase.
41. The compound responsible for the smell of bananas is –
(A) Isoamyl acetate
(B) Ethanol
(C) Acetone
(D) Toluene
Answer: (A)
Explanation: Isoamyl acetate (CH₃COOCH₂CH₂CH(CH₃)₂) is an ester responsible for the characteristic banana-like odor.
42. The crystal structure of quartz (SiO₂) is –
(A) Hexagonal
(B) Cubic
(C) Orthorhombic
(D) Tetragonal
Answer: (A)
Explanation: Quartz (SiO₂) has a hexagonal crystal structure, with silicon atoms tetrahedrally coordinated by oxygen atoms.
43. The gas used in airships historically was –
(A) Helium
(B) Hydrogen
(C) Neon
(D) Argon
Answer: (B)
Explanation: Hydrogen was used in airships (e.g., Hindenburg) for buoyancy, though helium is now preferred due to safety.
44. The common name for propanoic acid is –
(A) Formic acid
(B) Acetic acid
(C) Propionic acid
(D) Butyric acid
Answer: (C)
Explanation: Propanoic acid (CH₃CH₂COOH) is commonly known as propionic acid, used as a preservative.
45. The phenomenon of bending of light around 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 photoelectric cells is –
(A) Cesium
(B) Sodium
(C) Potassium
(D) All of the above
Answer: (D)
Explanation: Cesium, sodium, and potassium are used in photoelectric cells due to their low ionization energies, enabling electron emission upon light exposure.
47. The formula of quicklime is –
(A) CaCO₃
(B) CaO
(C) Ca(OH)₂
(D) CaSO₄
Answer: (B)
Explanation: Quicklime is calcium oxide (CaO), used in cement production and as a base.
48. The oxidation number of phosphorus in P₂O₅ is –
(A) +3
(B) +4
(C) +5
(D) +6
Answer: (C)
Explanation: In P₂O₅, O = -2. Let P = x. Then, 2x + 5(-2) = 0 → 2x – 10 = 0 → x = +5.
49. Which of the following is a conjugate acid?
(A) HCO₃⁻
(B) NH₃
(C) NH₄⁺
(D) OH⁻
Answer: (C)
Explanation: A conjugate acid is formed by gaining a proton. NH₄⁺ is the conjugate acid of NH₃, unlike the others, which are bases or anions.
50. The IUPAC name of CH₃COOCH₂CH₃ is –
(A) Methyl ethanoate
(B) Ethyl ethanoate
(C) Methyl methanoate
(D) Ethyl methanoate
Answer: (B)
Explanation: CH₃COOCH₂CH₃ is an ester with an ethyl group on the alkoxy side and an ethanoyl group, so its IUPAC name is ethyl ethanoate.