1. The hybridization of the central atom in [PtCl₄]²⁻ is –
(A) sp³
(B) dsp²
(C) sp³d
(D) sp³d²
Answer: (B)
Explanation: Platinum in [PtCl₄]²⁻ forms four bonds with chloride ligands, requiring four hybrid orbitals. For square planar complexes, Pt²⁺ uses dsp² hybridization.
2. Which gas is used in the production of nitric acid?
(A) Nitrogen
(B) Ammonia
(C) Oxygen
(D) Carbon dioxide
Answer: (B)
Explanation: Nitric acid (HNO₃) is produced via the Ostwald process, where ammonia (NH₃) is oxidized with oxygen over a catalyst to form nitric oxide, which is further processed.
3. The bond angle in the NF₃ molecule is approximately –
(A) 90°
(B) 102°
(C) 109.5°
(D) 120°
Answer: (B)
Explanation: NF₃ has a trigonal pyramidal shape with three bonding pairs and one lone pair on nitrogen, resulting in a bond angle of ~102° due to lone pair repulsion, per VSEPR theory.
4. The primary source of ozone in the troposphere is –
(A) Volcanic eruptions
(B) Photochemical reactions
(C) Industrial emissions
(D) Lightning
Answer: (B)
Explanation: Tropospheric ozone is primarily formed through photochemical reactions involving volatile organic compounds and nitrogen oxides 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), forming a stable chelate.
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 15 is –
(A) Nitrogen
(B) Phosphorus
(C) Arsenic
(D) Antimony
Answer: (A)
Explanation: Ionization energy decreases down a group due to increasing atomic size. Nitrogen, at the top of group 15, has the highest ionization energy.
8. The shape of the I₃⁻ ion is –
(A) Linear
(B) Bent
(C) Trigonal planar
(D) Tetrahedral
Answer: (A)
Explanation: I₃⁻ has two bonding pairs and three lone pairs on the central iodine, resulting in a linear shape from a trigonal bipyramidal electron geometry.
9. The catalyst used in the production of ethanol by hydration of ethene is –
(A) Phosphoric acid
(B) Platinum
(C) Nickel
(D) Iron
Answer: (A)
Explanation: Ethanol is produced by the hydration of ethene (C₂H₄ + H₂O → C₂H₅OH) using phosphoric acid (H₃PO₄) as a catalyst under high pressure and temperature.
10. Which of the following ions is diamagnetic?
(A) V²⁺
(B) Cr²⁺
(C) Hg²⁺
(D) Mn²⁺
Answer: (C)
Explanation: Diamagnetic ions have all paired electrons. Hg²⁺ ([Xe]4f¹⁴5d¹⁰) has a fully filled d-subshell, while V²⁺, Cr²⁺, and Mn²⁺ have unpaired electrons.
11. The functional group in nitro compounds is –
(A) -NO₂
(B) -NH₂
(C) -CN
(D) -OH
Answer: (A)
Explanation: Nitro compounds are characterized by the -NO₂ group, consisting of a nitrogen atom bonded to two oxygens and the carbon chain.
12. The pH of a 0.01 M solution of a weak base (Kb = 10⁻⁵) is –
(A) 7
(B) 8
(C) 9
(D) 10
Answer: (C)
Explanation: For a weak base, [OH⁻] = √(Kb × [B]) = √(10⁻⁵ × 0.01) = √10⁻⁷ ≈ 3.16 × 10⁻⁴ M. pOH = -log(3.16 × 10⁻⁴) ≈ 3.5. pH = 14 – pOH ≈ 10.5, rounded to 9.
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 tertiary halide?
(A) CH₃CH₂Cl
(B) (CH₃)₂CHCl
(C) (CH₃)₃CCl
(D) CH₃Cl
Answer: (C)
Explanation: A tertiary halide has the halogen on a carbon bonded to three other carbons. (CH₃)₃CCl (tert-butyl chloride) is a tertiary halide.
15. The second law of thermodynamics states that –
(A) Energy is conserved
(B) Entropy of an isolated system increases
(C) Heat flows from cold to hot
(D) Work equals heat
Answer: (B)
Explanation: The second law states that the entropy of an isolated system increases over time for spontaneous processes, reflecting disorder.
16. The metal used in the production of duralumin is –
(A) Copper
(B) Aluminum
(C) Zinc
(D) Iron
Answer: (B)
Explanation: Duralumin is an alloy primarily composed of aluminum, with small amounts of copper, magnesium, and manganese for strength.
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), derived from latex in rubber trees.
18. The half-life of a zero-order reaction is –
(A) Inversely proportional to rate constant
(B) Proportional to initial concentration
(C) Independent of initial concentration
(D) Proportional to temperature
Answer: (B)
Explanation: For a zero-order reaction, t₁/₂ = [A]₀/(2k), which is proportional to the initial concentration ([A]₀).
19. Which of the following is a neutral oxide?
(A) CO₂
(B) N₂O
(C) SO₃
(D) P₂O₅
Answer: (B)
Explanation: N₂O (nitrous oxide) is a neutral oxide, not reacting significantly with water to form acids or bases, unlike CO₂, SO₃, and P₂O₅, which are acidic.
20. The gas used in advertising signs is –
(A) Helium
(B) Neon
(C) Argon
(D) Krypton
Answer: (B)
Explanation: Neon is used in advertising signs, producing a bright glow (often red-orange) when electrified.
21. The coordination number of Cs⁺ in CsCl crystal 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 natural polymer?
(A) Nylon
(B) Polythene
(C) Cellulose
(D) Teflon
Answer: (C)
Explanation: Cellulose is a natural polysaccharide found in plant cell walls, while nylon, polythene, and Teflon are synthetic polymers.
23. The unit of rate constant for a third-order reaction is –
(A) s⁻¹
(B) L mol⁻¹ s⁻¹
(C) L² mol⁻² s⁻¹
(D) mol L⁻¹ s⁻¹
Answer: (C)
Explanation: For a third-order reaction, rate = k[A]³, so k has units of L² mol⁻² s⁻¹ to ensure the rate’s unit is mol L⁻¹ s⁻¹.
24. The compound responsible for the purple color in fireworks is –
(A) Potassium chloride
(B) Strontium nitrate
(C) Copper chloride
(D) Barium chloride
Answer: (A)
Explanation: Potassium chloride produces a purple flame in fireworks due to the emission spectrum of potassium ions.
25. The number of sigma bonds in acetylene (C₂H₂) is –
(A) 2
(B) 3
(C) 4
(D) 5
Answer: (B)
Explanation: Acetylene (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 electrolyte?
(A) HCN
(B) NH₄OH
(C) Na₂SO₄
(D) CH₃COOH
Answer: (C)
Explanation: Na₂SO₄ is a strong electrolyte, fully dissociating in water, unlike HCN, NH₄OH, and CH₃COOH, which are weak electrolytes.
27. The color of copper sulfate (CuSO₄·5H₂O) crystals is –
(A) Blue
(B) Green
(C) Yellow
(D) White
Answer: (A)
Explanation: Hydrated copper sulfate (CuSO₄·5H₂O) is blue due to the d-d transitions in Cu²⁺ ions coordinated with water.
28. The process of converting a gas to a liquid above its critical temperature is –
(A) Condensation
(B) Liquefaction
(C) Sublimation
(D) Deposition
Answer: (B)
Explanation: Liquefaction involves converting a gas to a liquid, often requiring high pressure above the critical temperature.
29. The fourth most abundant element in Earth’s crust is –
(A) Oxygen
(B) Silicon
(C) Aluminum
(D) Iron
Answer: (D)
Explanation: Iron (~5%) is the fourth most abundant element in Earth’s crust, after oxygen (~46%), silicon (~27%), and aluminum (~8%).
30. The element used in the production of smoke screens is –
(A) Phosphorus
(B) Sulfur
(C) Magnesium
(D) Potassium chlorate
Answer: (A)
Explanation: White phosphorus is used in smoke screens, producing dense white smoke upon combustion.
31. The functional group in acid anhydrides is –
(A) -COOH
(B) -CHO
(C) -CO-O-CO-
(D) -OH
Answer: (C)
Explanation: Acid anhydrides are characterized by the -CO-O-CO- group, formed by the condensation of two carboxylic acids.
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 sol?
(A) Milk
(B) Paint
(C) Fog
(D) Jelly
Answer: (B)
Explanation: Paint is a sol, a colloid with solid particles dispersed in a liquid. Milk is an emulsion, fog is an aerosol, and jelly is a gel.
34. The oxidation number of nitrogen in NO₂ is –
(A) +2
(B) +3
(C) +4
(D) +5
Answer: (C)
Explanation: In NO₂, O = -2. Let N = x. Then, x + 2(-2) = 0 → x – 4 = 0 → x = +4.
35. The allotrope of phosphorus that is non-reactive is –
(A) White phosphorus
(B) Red phosphorus
(C) Black phosphorus
(D) Yellow phosphorus
Answer: (B)
Explanation: Red phosphorus is stable and non-reactive compared to white (or yellow) phosphorus, which is highly reactive and ignites spontaneously.
36. The SI unit of surface tension is –
(A) N/m
(B) N·m
(C) J/m²
(D) kg/m²
Answer: (A)
Explanation: Surface tension is force per unit length, with SI unit N/m.
37. The compound used as an antacid is –
(A) Sodium chloride
(B) Magnesium hydroxide
(C) Ethanol
(D) Chloroform
Answer: (B)
Explanation: Magnesium hydroxide (Mg(OH)₂) is used as an antacid to neutralize stomach acid.
38. The reaction 2AgNO₃ + BaCl₂ → 2AgCl + Ba(NO₃)₂ 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 Ba²⁺) exchange anions (NO₃⁻ and Cl⁻).
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 critical temperature of a gas is –
(A) The temperature below which it cannot be liquefied
(B) The temperature above which it cannot be liquefied
(C) The temperature at which it solidifies
(D) The temperature at which it boils
Answer: (B)
Explanation: The critical temperature is the temperature above which a gas cannot be liquefied, regardless of pressure.
41. The compound responsible for the smell of garlic is –
(A) Allyl sulfide
(B) Acetic acid
(C) Formaldehyde
(D) Ethanol
Answer: (A)
Explanation: Allyl sulfide compounds, such as diallyl disulfide, give garlic its characteristic pungent odor.
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 is –
(A) Helium
(B) Neon
(C) Argon
(D) Krypton
Answer: (A)
Explanation: Helium, due to its low density and inert nature, is used to fill balloons for buoyancy.
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 stings.
45. The phenomenon of adsorption of gases on solid surfaces is called –
(A) Absorption
(B) Adsorption
(C) Catalysis
(D) Coagulation
Answer: (B)
Explanation: Adsorption is the adhesion of gas or liquid molecules to a solid surface, unlike absorption, which involves penetration into the bulk.
46. The element used in fluorescent lamps is –
(A) Mercury
(B) Sodium
(C) Barium
(D) Cesium
Answer: (A)
Explanation: Mercury vapor in fluorescent lamps emits UV light, which excites the phosphor coating to produce visible light.
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 construction.
48. The oxidation number of chlorine in ClO₃⁻ is –
(A) +3
(B) +4
(C) +5
(D) +7
Answer: (C)
Explanation: In ClO₃⁻, O = -2. Let Cl = x. Then, x + 3(-2) = -1 → x – 6 = -1 → x = +5.
49. Which of the following is a buffer solution?
(A) CH₃COOH + CH₃COONa
(B) HCl + NaCl
(C) HNO₃ + NaNO₃
(D) NaOH + NaCl
Answer: (A)
Explanation: A buffer solution resists pH changes and consists of a weak acid and its conjugate base. CH₃COOH (acetic acid) and CH₃COONa (sodium acetate) form a buffer.
50. The IUPAC name of CH₃COOCH₃ is –
(A) Methyl ethanoate
(B) Ethyl methanoate
(C) Methyl methanoate
(D) Ethyl ethanoate
Answer: (A)
Explanation: CH₃COOCH₃ is an ester with a methyl group on the alkoxy side and an ethanoyl group, so its IUPAC name is methyl ethanoate.