1. The hybridization of the central atom in [Fe(H₂O)₆]³⁺ is –
(A) sp³
(B) d²sp³
(C) sp³d²
(D) dsp²
Answer: (C)
Explanation: Iron in [Fe(H₂O)₆]³⁺ forms six bonds with water ligands in an octahedral geometry, requiring six hybrid orbitals. Fe³⁺ uses sp³d² hybridization for this arrangement.
2. Which gas is used in the production of ammonium nitrate?
(A) Nitrogen
(B) Ammonia
(C) Oxygen
(D) Carbon dioxide
Answer: (B)
Explanation: Ammonium nitrate (NH₄NO₃) is produced by reacting ammonia (NH₃) with nitric acid (HNO₃), typically derived from ammonia oxidation.
3. The bond angle in the SO₂ molecule is approximately –
(A) 90°
(B) 109.5°
(C) 119°
(D) 180°
Answer: (C)
Explanation: SO₂ has a bent shape with two bonding pairs and one lone pair on sulfur, resulting in a bond angle of ~119° due to lone pair repulsion, per VSEPR theory.
4. The primary source of nitrous oxide in the atmosphere is –
(A) Industrial emissions
(B) Agricultural soils
(C) Volcanic activity
(D) Combustion
Answer: (B)
Explanation: Nitrous oxide (N₂O), a greenhouse gas, is primarily released from agricultural soils due to microbial activity in nitrogen-rich fertilizers.
5. Which of the following is a tetradentate ligand?
(A) Ethylenediamine
(B) Triethylenetetramine
(C) Cyanide
(D) Oxalate
Answer: (B)
Explanation: Triethylenetetramine (trien) is a tetradentate ligand, binding to a metal ion at four nitrogen atoms, unlike ethylenediamine (bidentate), cyanide (monodentate), or oxalate (bidentate).
6. The rate constant of a reaction increases with –
(A) Decreasing temperature
(B) Increasing temperature
(C) Decreasing concentration
(D) Increasing volume
Answer: (B)
Explanation: Per the Arrhenius equation (k = Ae^(-Ea/RT)), the rate constant increases with temperature due to more molecules having sufficient energy to react.
7. The element with the highest melting point in group 14 is –
(A) Carbon
(B) Silicon
(C) Tin
(D) Lead
Answer: (A)
Explanation: Carbon (in diamond form) has the highest melting point in group 14 due to its strong covalent network structure.
8. The shape of the XeF₂ molecule is –
(A) Linear
(B) Bent
(C) Trigonal planar
(D) Tetrahedral
Answer: (A)
Explanation: XeF₂ has two bonding pairs and three lone pairs on xenon, resulting in a linear shape from a trigonal bipyramidal electron geometry.
9. The catalyst used in the production of acetaldehyde from acetylene is –
(A) Mercury(II) sulfate
(B) Platinum
(C) Nickel
(D) Iron
Answer: (A)
Explanation: Acetaldehyde (CH₃CHO) is produced by the hydration of acetylene (C₂H₂) using mercury(II) sulfate as a catalyst in acidic conditions.
10. Which of the following ions is paramagnetic?
(A) Ca²⁺
(B) Co²⁺
(C) Zn²⁺
(D) Sr²⁺
Answer: (B)
Explanation: Paramagnetic ions have unpaired electrons. Co²⁺ ([Ar]3d⁷) has three unpaired electrons, while Ca²⁺, Zn²⁺, and Sr²⁺ have fully paired or empty orbitals.
11. The functional group in aldehydes is –
(A) -CHO
(B) -COOH
(C) -OH
(D) -CO-
Answer: (A)
Explanation: Aldehydes are characterized by the -CHO group, with a carbonyl group bonded to at least one hydrogen.
12. The pH of a 0.01 M solution of a weak acid (Ka = 10⁻⁴) is –
(A) 2
(B) 3
(C) 4
(D) 5
Answer: (B)
Explanation: For a weak acid, [H⁺] = √(Ka × [HA]) = √(10⁻⁴ × 0.01) = √10⁻⁶ = 10⁻³ M. pH = -log(10⁻³) = 3.
13. The oxidation state of nickel in [Ni(en)₃]²⁺ is –
(A) +1
(B) +2
(C) +3
(D) +4
Answer: (B)
Explanation: Ethylenediamine (en) is a neutral ligand. The complex has a +2 charge. Let Ni = x. Then, x + 3(0) = +2 → x = +2.
14. Which of the following is a tertiary alcohol?
(A) CH₃CH₂OH
(B) (CH₃)₂CHOH
(C) (CH₃)₃COH
(D) C₆H₅CH₂OH
Answer: (C)
Explanation: A tertiary alcohol has the -OH group on a carbon bonded to three other carbons. (CH₃)₃COH (tert-butanol) is a tertiary alcohol.
15. The third law of thermodynamics states that –
(A) Energy is conserved
(B) Entropy of a perfect crystal at 0 K is zero
(C) Heat flows from hot to cold
(D) Work equals heat
Answer: (B)
Explanation: The third law states that the entropy of a perfect crystalline substance is zero at absolute zero (0 K), as there is no disorder.
16. The metal used in the production of gunmetal is –
(A) Copper
(B) Zinc
(C) Tin
(D) Both (A) and (C)
Answer: (D)
Explanation: Gunmetal is an alloy of copper, tin, and sometimes zinc, used for its strength and corrosion resistance.
17. The monomer of teflon is –
(A) Ethylene
(B) Vinyl chloride
(C) Tetrafluoroethylene
(D) Styrene
Answer: (C)
Explanation: Teflon (polytetrafluoroethylene) is a polymer of tetrafluoroethylene (C₂F₄), known for its non-stick properties.
18. The rate constant of a third-order reaction depends on –
(A) Concentration only
(B) Temperature only
(C) Both concentration and temperature
(D) Catalyst only
Answer: (B)
Explanation: The rate constant (k) depends on temperature via the Arrhenius equation, not on concentration, which affects the rate but not k.
19. Which of the following is a basic salt?
(A) NaCl
(B) Na₂CO₃
(C) NaH₂PO₄
(D) NH₄Cl
Answer: (B)
Explanation: Na₂CO₃, formed from a strong base (NaOH) and a weak acid (H₂CO₃), is a basic salt, producing OH⁻ in solution.
20. The gas used in high-pressure mercury lamps is –
(A) Argon
(B) Neon
(C) Mercury vapor
(D) Helium
Answer: (C)
Explanation: Mercury vapor is used in high-pressure mercury lamps, emitting UV and visible light when electrified.
21. The coordination number of Cu²⁺ in [Cu(NH₃)₄]²⁺ is –
(A) 4
(B) 6
(C) 8
(D) 12
Answer: (A)
Explanation: In [Cu(NH₃)₄]²⁺, Cu²⁺ is coordinated by four ammonia ligands in a square planar arrangement, giving a coordination number of 4.
22. Which of the following is a natural polymer?
(A) Nylon-6,6
(B) Polythene
(C) Chitin
(D) PVC
Answer: (C)
Explanation: Chitin, found in insect exoskeletons, is a natural polysaccharide, while nylon-6,6, polythene, and PVC are synthetic polymers.
23. The unit of ionic mobility is –
(A) m² V⁻¹ s⁻¹
(B) m V⁻¹ s⁻¹
(C) S m² mol⁻¹
(D) m² s⁻¹
Answer: (A)
Explanation: Ionic mobility is the velocity of an ion per unit electric field, with SI unit m² V⁻¹ s⁻¹.
24. The compound responsible for the blue color in glass is –
(A) Cobalt oxide
(B) Chromium oxide
(C) Iron oxide
(D) Manganese dioxide
Answer: (A)
Explanation: Cobalt oxide (CoO) imparts a blue color to glass, used in decorative and stained glass.
25. The number of pi bonds in propyne (C₃H₄) is –
(A) 1
(B) 2
(C) 3
(D) 4
Answer: (B)
Explanation: Propyne (CH₃C≡CH) has one triple bond (1 sigma + 2 pi). Total pi bonds = 2.
26. Which of the following is a weak base?
(A) NaOH
(B) KOH
(C) CH₃NH₂
(D) Ca(OH)₂
Answer: (C)
Explanation: Methylamine (CH₃NH₂) is a weak base, partially dissociating in water, unlike strong bases NaOH, KOH, and Ca(OH)₂.
27. The color of strontium nitrate flame in a flame test is –
(A) Green
(B) Red
(C) Blue
(D) Yellow
Answer: (B)
Explanation: Strontium ions produce a red flame in a flame test due to electron transitions in the strontium atom.
28. The process of converting a liquid to a solid is called –
(A) Sublimation
(B) Freezing
(C) Evaporation
(D) Condensation
Answer: (B)
Explanation: Freezing is the phase transition from liquid to solid, such as water to ice.
29. The most abundant metal in Earth’s crust is –
(A) Iron
(B) Aluminum
(C) Calcium
(D) Magnesium
Answer: (B)
Explanation: Aluminum (~8%) is the most abundant metal in Earth’s crust, found in minerals like bauxite.
30. The element used in the production of smoke bombs is –
(A) Potassium chlorate
(B) Sulfur
(C) Magnesium
(D) All of the above
Answer: (D)
Explanation: Smoke bombs use potassium chlorate (oxidizer), sulfur (fuel), and magnesium for dense smoke production.
31. The functional group in esters is –
(A) -COOH
(B) -CHO
(C) -COOR
(D) -OH
Answer: (C)
Explanation: Esters are characterized by the -COOR group, with a carbonyl bonded to an alkoxy group.
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) Cheese
(B) Milk
(C) Fog
(D) Paint
Answer: (A)
Explanation: Cheese 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 sulfur in H₂SO₄ is –
(A) +4
(B) +6
(C) +2
(D) -2
Answer: (B)
Explanation: In H₂SO₄, H = +1, O = -2. Let S = x. Then, 2(+1) + x + 4(-2) = 0 → 2 + x – 8 = 0 → x = +6.
35. The allotrope of carbon used in electrodes is –
(A) Diamond
(B) Graphite
(C) Fullerene
(D) Charcoal
Answer: (B)
Explanation: Graphite, due to its electrical conductivity from delocalized electrons, is used in electrodes.
36. The SI unit of molar conductivity is –
(A) S m² mol⁻¹
(B) S m⁻¹
(C) S m²
(D) S mol⁻¹
Answer: (A)
Explanation: Molar conductivity is conductivity divided by molar concentration, with SI unit S m² mol⁻¹.
37. The compound used as an anesthetic is –
(A) Ethanol
(B) Chloroform
(C) Sodium chloride
(D) Formaldehyde
Answer: (B)
Explanation: Chloroform (CHCl₃) was historically used as an anesthetic, though safer alternatives are now used.
38. The reaction Zn + 2AgNO₃ → Zn(NO₃)₂ + 2Ag is an example of –
(A) Combination
(B) Decomposition
(C) Displacement
(D) Double displacement
Answer: (C)
Explanation: This is a displacement reaction, where zinc displaces silver from silver nitrate due to its higher reactivity.
39. The element with atomic number 18 belongs to –
(A) Alkali metals
(B) Halogens
(C) Noble gases
(D) Alkaline earth metals
Answer: (C)
Explanation: Atomic number 18 corresponds to argon, in group 18 (noble gases).
40. The vapor pressure of a liquid decreases with –
(A) Increasing temperature
(B) Decreasing temperature
(C) Increasing pressure
(D) Decreasing volume
Answer: (B)
Explanation: Vapor pressure decreases with decreasing temperature, as fewer molecules have sufficient energy to enter the gas phase.
41. The compound responsible for the smell of pineapples is –
(A) Ethyl butanoate
(B) Isoamyl acetate
(C) Ethanol
(D) Acetone
Answer: (A)
Explanation: Ethyl butanoate is an ester responsible for the pineapple-like odor.
42. The crystal structure of cesium chloride (CsCl) is –
(A) Face-centered cubic
(B) Body-centered cubic
(C) Hexagonal
(D) Orthorhombic
Answer: (B)
Explanation: CsCl has a body-centered cubic structure, with each Cs⁺ ion surrounded by eight Cl⁻ ions.
43. The gas used in cryogenics is –
(A) Helium
(B) Neon
(C) Argon
(D) Krypton
Answer: (A)
Explanation: Liquid helium is used in cryogenics due to its extremely low boiling point (~4 K).
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 (CH₃CH₂CH₂COOH) is commonly known as butyric acid, responsible for the odor of rancid butter.
45. The phenomenon of movement of solvent molecules through a semipermeable membrane is –
(A) Osmosis
(B) Diffusion
(C) Effusion
(D) Electrophoresis
Answer: (A)
Explanation: Osmosis is the movement of solvent molecules through a semipermeable membrane from a region of lower to higher solute concentration.
46. The element used in LEDs is –
(A) Gallium
(B) Silicon
(C) Germanium
(D) All of the above
Answer: (D)
Explanation: Gallium (in GaAs), silicon, and germanium are used in LEDs for their semiconductor properties.
47. The formula of gypsum is –
(A) CaSO₄
(B) CaSO₄·½H₂O
(C) CaSO₄·2H₂O
(D) Ca(OH)₂
Answer: (C)
Explanation: Gypsum is calcium sulfate dihydrate (CaSO₄·2H₂O), used in plaster production.
48. The oxidation number of nitrogen in N₂O₅ is –
(A) +3
(B) +4
(C) +5
(D) +6
Answer: (C)
Explanation: In N₂O₅, O = -2. Let N = x. Then, 2x + 5(-2) = 0 → 2x – 10 = 0 → x = +5.
49. Which of the following is a redox reaction?
(A) NaCl + AgNO₃ → AgCl + NaNO₃
(B) 2H₂ + O₂ → 2H₂O
(C) HCl + NaOH → NaCl + H₂O
(D) CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂
Answer: (B)
Explanation: 2H₂ + O₂ → 2H₂O involves a change in oxidation states (H: 0 to +1, O: 0 to -2), making it a redox reaction. The others are not.
50. The IUPAC name of CH₃CH₂COOCH₃ is –
(A) Methyl propanoate
(B) Ethyl propanoate
(C) Methyl ethanoate
(D) Ethyl methanoate
Answer: (A)
Explanation: CH₃CH₂COOCH₃ is an ester with a methyl group on the alkoxy side and a propanoyl group, so its IUPAC name is methyl propanoate.