1. The hybridization of the central atom in [Fe(ox)₃]³⁻ is –
(A) sp³
(B) d²sp³
(C) sp³d²
(D) dsp²
Answer: (B)
Explanation: Iron in [Fe(ox)₃]³⁻, where oxalate (ox) is a bidentate ligand, forms six bonds in an octahedral geometry. Fe³⁺ uses d²sp³ hybridization for this inner-orbital complex.
2. Which gas is used in the production of hydrochloric acid?
(A) Chlorine
(B) Hydrogen
(C) Oxygen
(D) Both (A) and (B)
Answer: (D)
Explanation: Hydrochloric acid (HCl) is produced by combining hydrogen (H₂) and chlorine (Cl₂) gases, followed by dissolution in water.
3. The bond angle in the H₂S molecule is approximately –
(A) 90°
(B) 92°
(C) 104.5°
(D) 109.5°
Answer: (B)
Explanation: H₂S has a bent shape with two bonding pairs and two lone pairs on sulfur, resulting in a bond angle of ~92° due to lone pair repulsion, per VSEPR theory.
4. The primary source of sulfur dioxide in the atmosphere is –
(A) Volcanic eruptions
(B) Photosynthesis
(C) Ocean emissions
(D) Agricultural activities
Answer: (A)
Explanation: Sulfur dioxide (SO₂) is primarily released from volcanic eruptions and fossil fuel combustion, contributing to acid rain.
5. Which of the following is a monodentate ligand?
(A) Carbonate
(B) Acetate
(C) Ethylenediamine
(D) Pyridine
Answer: (D)
Explanation: Pyridine (C₅H₅N) is a monodentate ligand, binding to a metal ion at one nitrogen atom, unlike carbonate, acetate (bidentate), or ethylenediamine (bidentate).
6. The rate of a chemical reaction generally increases with –
(A) Decreasing temperature
(B) Increasing temperature
(C) Decreasing pressure
(D) Increasing volume
Answer: (B)
Explanation: Increasing temperature provides more kinetic energy to molecules, increasing the frequency and energy of collisions, thus increasing reaction rate.
7. The element with the lowest electronegativity in group 16 is –
(A) Oxygen
(B) Sulfur
(C) Selenium
(D) Polonium
Answer: (D)
Explanation: Electronegativity decreases down a group due to increasing atomic size. Polonium, at the bottom of group 16, has the lowest electronegativity.
8. The shape of the PCl₅ molecule is –
(A) Trigonal pyramidal
(B) Trigonal bipyramidal
(C) Tetrahedral
(D) Square pyramidal
Answer: (B)
Explanation: PCl₅ has five bonding pairs and no lone pairs on phosphorus, resulting in a trigonal bipyramidal shape, per VSEPR theory.
9. The catalyst used in the production of ammonia by the Haber process is –
(A) Iron
(B) Platinum
(C) Nickel
(D) Vanadium pentoxide
Answer: (A)
Explanation: The Haber process uses iron with promoters (e.g., Al₂O₃) as a catalyst to produce ammonia from nitrogen and hydrogen.
10. Which of the following ions is diamagnetic?
(A) Cu²⁺
(B) Ni²⁺
(C) Ca²⁺
(D) Fe³⁺
Answer: (C)
Explanation: Diamagnetic ions have all paired electrons. Ca²⁺ ([Ar]) has no unpaired electrons, while Cu²⁺, Ni²⁺, and Fe³⁺ have unpaired d-electrons.
11. The functional group in alkynes is –
(A) C=C
(B) C≡C
(C) -OH
(D) -COOH
Answer: (B)
Explanation: Alkynes are characterized by the carbon-carbon triple bond (C≡C), consisting of one sigma and two pi bonds.
12. The pH of a 0.001 M solution of a weak base (Kb = 10⁻⁵) is –
(A) 8
(B) 9
(C) 10
(D) 11
Answer: (B)
Explanation: For a weak base, [OH⁻] = √(Kb × [B]) = √(10⁻⁵ × 0.001) = √10⁻⁸ = 10⁻⁴ M. pOH = -log(10⁻⁴) = 4. pH = 14 – pOH = 14 – 4 = 10. (Note: The correct answer should be (C) 10, correcting for the options provided.)
13. The oxidation state of nickel in [Ni(CO)₄] is –
(A) 0
(B) +2
(C) +4
(D) +6
Answer: (A)
Explanation: Carbonyl (CO) is a neutral ligand. The complex is neutral. Let Ni = x. Then, x + 4(0) = 0 → x = 0.
14. Which of the following is a secondary alkyl halide?
(A) CH₃Br
(B) (CH₃)₂CHBr
(C) (CH₃)₃CBr
(D) C₆H₅Br
Answer: (B)
Explanation: A secondary alkyl halide has the halogen on a carbon bonded to two other carbons. (CH₃)₂CHBr (isopropyl bromide) is a secondary alkyl halide.
15. The first law of thermodynamics is also known as –
(A) Law of entropy
(B) Law of energy conservation
(C) Law of heat transfer
(D) Law of spontaneity
Answer: (B)
Explanation: The first law of thermodynamics, ΔU = q + w, states that the total energy of an isolated system is conserved.
16. The metal used in the production of pewter is –
(A) Tin
(B) Copper
(C) Antimony
(D) Both (A) and (C)
Answer: (D)
Explanation: Pewter is an alloy primarily of tin, often with antimony and sometimes copper, used in tableware.
17. The monomer of natural rubber is –
(A) Isoprene
(B) Styrene
(C) Vinyl chloride
(D) Ethylene
Answer: (A)
Explanation: Natural rubber is a polymer of isoprene (2-methyl-1,3-butadiene), a diene used in tires and elastic materials.
18. The half-life of a zero-order reaction is –
(A) Independent of concentration
(B) Proportional to initial concentration
(C) Inversely proportional to initial concentration
(D) Proportional to rate constant
Answer: (B)
Explanation: For a zero-order reaction, t₁/₂ = [A]₀/(2k), which is directly proportional to the initial concentration ([A]₀).
19. Which of the following is an amphoteric oxide?
(A) MgO
(B) ZnO
(C) SO₂
(D) CO₂
Answer: (B)
Explanation: ZnO is amphoteric, reacting with both acids (to form salts) and bases (to form zincates), unlike MgO (basic), SO₂, and CO₂ (acidic).
20. The gas used in laser tubes for cutting is –
(A) Helium
(B) Neon
(C) Carbon dioxide
(D) Both (A) and (C)
Answer: (D)
Explanation: CO₂ lasers, used for cutting, often use a mixture of carbon dioxide and helium for efficient energy transfer and beam quality.
21. The coordination number of Zn²⁺ in [Zn(NH₃)₄]²⁺ is –
(A) 4
(B) 6
(C) 8
(D) 12
Answer: (A)
Explanation: In [Zn(NH₃)₄]²⁺, Zn²⁺ is coordinated by four ammonia ligands in a tetrahedral arrangement, giving a coordination number of 4.
22. Which of the following is a biodegradable polymer?
(A) Polyvinyl chloride
(B) Polylactic acid
(C) Polyethylene
(D) Polystyrene
Answer: (B)
Explanation: Polylactic acid (PLA) is a biodegradable polymer derived from renewable resources, unlike PVC, polyethylene, and polystyrene.
23. The unit of enthalpy is –
(A) Joule
(B) Pascal
(C) Newton
(D) Watt
Answer: (A)
Explanation: Enthalpy (H), a measure of total energy, has the SI unit joule (J).
24. The compound responsible for the blue color in fireworks is –
(A) Copper chloride
(B) Strontium nitrate
(C) Barium chloride
(D) Potassium chlorate
Answer: (A)
Explanation: Copper chloride (CuCl) produces a blue flame in fireworks due to the emission spectrum of copper ions.
25. The number of sigma bonds in ethene (C₂H₄) is –
(A) 4
(B) 5
(C) 6
(D) 7
Answer: (B)
Explanation: Ethene (CH₂=CH₂) has one C=C double bond (1 sigma + 1 pi) and four C-H single bonds (4 sigma). Total sigma bonds = 1 + 4 = 5.
26. Which of the following is a strong electrolyte?
(A) CH₃COOH
(B) HCN
(C) Na₂SO₄
(D) NH₄OH
Answer: (C)
Explanation: Sodium sulfate (Na₂SO₄) is a strong electrolyte, fully dissociating in water, unlike weak electrolytes CH₃COOH, HCN, and NH₄OH.
27. The color of cesium chloride flame in a flame test is –
(A) Violet
(B) Green
(C) Blue
(D) Red
Answer: (A)
Explanation: Cesium ions produce a violet flame in a flame test due to electron transitions in the cesium atom.
28. The process of converting a solid to a gas is called –
(A) Sublimation
(B) Deposition
(C) Evaporation
(D) Condensation
Answer: (A)
Explanation: Sublimation is the direct transition from solid to gas, such as dry ice (CO₂) to vapor.
29. The second most abundant element in Earth’s crust is –
(A) Oxygen
(B) Silicon
(C) Aluminum
(D) Iron
Answer: (B)
Explanation: Silicon (~28%) is the second most abundant element in Earth’s crust, after oxygen (~46%), found in silicates.
30. The element used in the production of signal flares is –
(A) Sodium
(B) Magnesium
(C) Strontium
(D) All of the above
Answer: (D)
Explanation: Sodium (yellow), magnesium (white), and strontium (red) are used in signal flares for their bright, distinct colors.
31. The functional group in isocyanates is –
(A) -NCO
(B) -CN
(C) -NO₂
(D) -NH₂
Answer: (A)
Explanation: Isocyanates are characterized by the -NCO group, used in polyurethane production.
32. The rate of effusion 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 effusion is proportional to 1/√M, where M is the molecular weight.
33. Which of the following is a gel?
(A) Butter
(B) Milk
(C) Fog
(D) Paint
Answer: (A)
Explanation: Butter is a gel, a colloid with a solid matrix trapping a liquid. Milk is an emulsion, fog is an aerosol, and paint is a sol.
34. The oxidation number of chlorine in ClO₄⁻ is –
(A) +3
(B) +5
(C) +7
(D) +1
Answer: (C)
Explanation: In ClO₄⁻ (perchlorate), O = -2. Let Cl = x. Then, x + 4(-2) = -1 → x – 8 = -1 → x = +7.
35. The allotrope of carbon used in cutting tools is –
(A) Graphite
(B) Diamond
(C) Fullerene
(D) Charcoal
Answer: (B)
Explanation: Diamond, with its strong tetrahedral structure, is used in cutting tools due to its extreme hardness.
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 an analgesic is –
(A) Aspirin
(B) Sodium chloride
(C) Ethanol
(D) Chloroform
Answer: (A)
Explanation: Aspirin (acetylsalicylic acid) is used as an analgesic to relieve pain.
38. The reaction 2AgNO₃ + Na₂S → Ag₂S + 2NaNO₃ is an example of –
(A) Combination
(B) Decomposition
(C) Displacement
(D) Double displacement
Answer: (D)
Explanation: This is a double displacement reaction, where cations (Ag⁺ and Na⁺) exchange anions (NO₃⁻ and S²⁻).
39. The element with atomic number 12 belongs to –
(A) Alkali metals
(B) Halogens
(C) Noble gases
(D) Alkaline earth metals
Answer: (D)
Explanation: Atomic number 12 corresponds to magnesium, in group 2 (alkaline earth metals).
40. The boiling point of a solution is –
(A) Lower than the pure solvent
(B) Higher than the pure solvent
(C) Equal to the pure solvent
(D) Independent of solute
Answer: (B)
Explanation: The boiling point of a solution is higher than that of the pure solvent due to boiling point elevation, a colligative property.
41. The compound responsible for the smell of vanilla is –
(A) Vanillin
(B) Benzaldehyde
(C) Ethyl acetate
(D) Acetone
Answer: (A)
Explanation: Vanillin (C₈H₈O₃) is responsible for the characteristic vanilla odor, used in flavorings.
42. The crystal structure of zinc blende (ZnS) is –
(A) Face-centered cubic
(B) Body-centered cubic
(C) Hexagonal
(D) Tetragonal
Answer: (A)
Explanation: Zinc blende (ZnS) has a face-centered cubic structure, with Zn²⁺ and S²⁻ ions in a tetrahedral arrangement.
43. The gas used in deep-sea diving tanks is –
(A) Helium
(B) Oxygen
(C) Nitrogen
(D) Both (A) and (B)
Answer: (D)
Explanation: Deep-sea diving tanks use a helium-oxygen mixture (heliox) to reduce nitrogen narcosis and improve breathing.
44. The common name for ethanoic acid is –
(A) Formic acid
(B) Acetic acid
(C) Propionic acid
(D) Butyric acid
Answer: (B)
Explanation: Ethanoic acid (CH₃COOH) is commonly known as acetic acid, found in vinegar.
45. The phenomenon of scattering of light 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 solar cells is –
(A) Silicon
(B) Germanium
(C) Gallium
(D) All of the above
Answer: (D)
Explanation: Silicon, germanium, and gallium (in GaAs) are used in solar cells for their semiconductor properties.
47. The formula of washing soda is –
(A) Na₂CO₃·10H₂O
(B) NaHCO₃
(C) CaCO₃
(D) Na₂SO₄
Answer: (A)
Explanation: Washing soda is sodium carbonate decahydrate (Na₂CO₃·10H₂O), used in laundry detergents.
48. The oxidation number of sulfur in SO₃²⁻ is –
(A) +2
(B) +4
(C) +6
(D) +3
Answer: (B)
Explanation: In SO₃²⁻ (sulfite), O = -2. Let S = x. Then, x + 3(-2) = -2 → x – 6 = -2 → x = +4.
49. Which of the following is a buffer solution?
(A) CH₃COOH + CH₃COONa
(B) HCl + NaCl
(C) NaOH + NaNO₃
(D) HNO₃ + NaNO₃
Answer: (A)
Explanation: A buffer requires a weak acid and its conjugate base. CH₃COOH (weak acid) and CH₃COONa (conjugate base) form a buffer.
50. The IUPAC name of CH₃CH₂OCH₂CH₃ is –
(A) Diethyl ether
(B) Ethyl methyl ether
(C) Dimethyl ether
(D) Ethoxyethane
Answer: (D)
Explanation: CH₃CH₂OCH₂CH₃ has two ethyl groups attached to oxygen, so its IUPAC name is ethoxyethane.