PYQ-Based | State Board | Polytechnic | Semester 1 & 2
1. The atomic number of an element is determined by:
a) Number of neutrons
b) Number of electrons
c) Number of protons
d) Sum of protons and neutrons
View Answer
c) Number of protons
Explanation: Atomic number (Z) is the number of protons in the nucleus, which defines the identity of the element.
2. Which of the following is not a postulate of Dalton’s atomic theory?
a) Atoms are indivisible
b) Atoms of same element are identical
c) Atoms can be created or destroyed
d) Atoms combine in simple whole number ratios
View Answer
c) Atoms can be created or destroyed
Explanation: Dalton proposed that atoms are indestructible. This was later modified by nuclear reactions.
3. The maximum number of electrons in the M-shell (n=3) is:
a) 2
b) 8
c) 18
d) 32
View Answer
c) 18
Explanation: Maximum electrons = 2n². For n=3, 2×9 = 18.
4. The electronic configuration of sodium (Na, Z=11) is:
a) 2,8,1
b) 2,8,2
c) 2,7,2
d) 2,8,3
View Answer
a) 2,8,1
Explanation: K-shell: 2, L-shell: 8, M-shell: 1.
5. Isotopes differ in the number of:
a) Protons
b) Electrons
c) Neutrons
d) Nucleons
View Answer
c) Neutrons
Explanation: Isotopes have same atomic number (protons) but different mass number (neutrons).
6. The valency of carbon in methane (CH₄) is:
a) 1
b) 2
c) 3
d) 4
View Answer
d) 4
Explanation: Carbon shares 4 electrons with 4 hydrogen atoms → tetravalent.
7. The law of definite proportions was proposed by:
a) Dalton
b) Proust
c) Lavoisier
d) Berzelius
View Answer
b) Proust
Explanation: A compound always contains the same elements in a fixed ratio by mass.
8. One mole of any substance contains:
a) 6.022 × 10²² particles
b) 6.022 × 10²³ particles
c) 6.022 × 10²⁴ particles
d) 6.022 × 10²⁵ particles
View Answer
b) 6.022 × 10²³ particles
Explanation: Avogadro’s number (Nₐ) = 6.022 × 10²³ mol⁻¹.
9. The molecular mass of H₂SO₄ is:
a) 98 u
b) 90 u
c) 82 u
d) 100 u
View Answer
a) 98 u
Explanation: (2×1) + 32 + (4×16) = 2 + 32 + 64 = 98 u.
10. The number of moles in 18 g of water is:
a) 1
b) 2
c) 0.5
d) 18
View Answer
a) 1
Explanation: Molar mass of H₂O = 18 g/mol → n = mass/molar mass = 18/18 = 1 mol.
11. The SI unit of amount of substance is:
a) Gram
b) Kilogram
c) Mole
d) Liter
View Answer
c) Mole
Explanation: Mole is the SI unit for amount of substance.
12. The gas that does not obey ideal gas law at all conditions is:
a) He
b) H₂
c) CO₂
d) All obey
View Answer
c) CO₂
Explanation: Real gases deviate at high pressure and low temperature. CO₂ liquefies easily.
13. The volume occupied by 1 mole of ideal gas at STP is:
a) 22.4 L
b) 11.2 L
c) 44.8 L
d) 2.24 L
View Answer
a) 22.4 L
Explanation: Molar volume at STP (0°C, 1 atm) = 22.4 L/mol.
14. According to Boyle’s law, PV =
a) Constant at constant T
b) Constant at constant n
c) Both a and b
d) None
View Answer
c) Both a and b
Explanation: PV = k (T and n constant).
15. The unit of gas constant (R) in SI system is:
a) J/mol·K
b) L·atm/mol·K
c) cal/mol·K
d) erg/mol·K
View Answer
a) J/mol·K
Explanation: R = 8.314 J/mol·K.
16. The oxidation state of oxygen in H₂O₂ is:
a) -1
b) -2
c) 0
d) +1
View Answer
a) -1
Explanation: 2H + 2O = 0 → 2(+1) + 2x = 0 → x = -1.
17. The strongest oxidizing agent among the following is:
a) Cl⁻
b) Br⁻
c) I⁻
d) F⁻
View Answer
d) F⁻
Explanation: F₂ has highest reduction potential → strongest oxidizing agent.
18. In redox reaction, the substance that gains electrons is:
a) Oxidized
b) Reduced
c) Neutral
d) None
View Answer
b) Reduced
Explanation: Reduction = gain of electrons.
19. The equivalent weight of KMnO₄ in acidic medium is:
a) 158
b) 52.67
c) 31.6
d) 79
View Answer
c) 31.6
Explanation: MnO₄⁻ → Mn²⁺ (5e⁻ change), M = 158 → Eq. wt. = 158/5 = 31.6.
20. The pH of 0.1 M HCl solution is:
a) 1
b) 2
c) 0.1
d) 7
View Answer
a) 1
Explanation: HCl → H⁺ + Cl⁻, [H⁺] = 0.1 M → pH = -log(0.1) = 1.
21. The conjugate base of H₂PO₄⁻ is:
a) HPO₄²⁻
b) PO₄³⁻
c) H₃PO₄
d) PH₃
View Answer
a) HPO₄²⁻
Explanation: H₂PO₄⁻ ⇌ H⁺ + HPO₄²⁻.
22. The solubility product (Ksp) is applicable to:
a) Soluble salts
b) Sparingly soluble salts
c) Gases
d) Liquids
View Answer
b) Sparingly soluble salts
Explanation: Ksp = [Mⁿ⁺][Aⁿ⁻] for saturated solution of MA.
23. The common ion effect is used in:
a) Increasing solubility
b) Decreasing solubility
c) No effect
d) Precipitation only
View Answer
b) Decreasing solubility
Explanation: Adding common ion shifts equilibrium → ↓ solubility.
24. The indicator used in strong acid–strong base titration is:
a) Methyl orange
b) Phenolphthalein
c) Both
d) None
View Answer
c) Both
Explanation: Sharp end point at pH 7.
25. The normality of 0.1 M H₂SO₄ is:
a) 0.1 N
b) 0.2 N
c) 0.05 N
d) 1 N
View Answer
b) 0.2 N
Explanation: H₂SO₄ → 2H⁺, n-factor = 2 → N = M × 2 = 0.2 N.
26. The hybridization in methane (CH₄) is:
a) sp
b) sp²
c) sp³
d) dsp²
View Answer
c) sp³
Explanation: Tetrahedral geometry → sp³ hybridization.
27. The shape of PCl₅ molecule is:
a) Trigonal planar
b) Trigonal bipyramidal
c) Tetrahedral
d) Octahedral
View Answer
b) Trigonal bipyramidal
Explanation: 5 bond pairs → sp³d hybridization.
28. The bond angle in water molecule is approximately:
a) 180°
b) 120°
c) 109.5°
d) 104.5°
View Answer
d) 104.5°
Explanation: Due to lone pair repulsion, less than tetrahedral angle.
29. Hydrogen bonding is maximum in:
a) H₂S
b) H₂O
c) H₂Se
d) H₂Te
View Answer
b) H₂O
Explanation: High electronegativity of O and small size → strong H-bonding.
30. The weakest intermolecular force is:
a) Hydrogen bond
b) Dipole-dipole
c) London dispersion
d) Ionic
View Answer
c) London dispersion
Explanation: Present in all molecules, weakest force.
31. The oxidation state of Cr in K₂Cr₂O₇ is:
a) +6
b) +7
c) +3
d) +12
View Answer
a) +6
Explanation: 2K + 2Cr + 7O = 0 → 2(+1) + 2x + 7(-2) = 0 → x = +6.
32. The catalyst used in contact process for H₂SO₄ is:
a) Fe
b) Pt
c) V₂O₅
d) Ni
View Answer
c) V₂O₅
Explanation: 2SO₂ + O₂ → 2SO₃ (V₂O₅ catalyst).
33. The ore of aluminum is:
a) Hematite
b) Bauxite
c) Galena
d) Cinnabar
View Answer
b) Bauxite
Explanation: Al₂O₃·2H₂O.
34. The monomer of PVC is:
a) Ethylene
b) Styrene
c) Vinyl chloride
d) Tetrafluoroethylene
View Answer
c) Vinyl chloride
Explanation: CH₂=CHCl → [–CH₂–CHCl–]ₙ.
35. The functional group in alcohol is:
a) –CHO
b) –COOH
c) –OH
d) –NH₂
View Answer
c) –OH
Explanation: Hydroxyl group.
36. The IUPAC name of CH₃CH₂OH is:
a) Methanol
b) Ethanol
c) Propanol
d) Butanol
View Answer
b) Ethanol
Explanation: C₂H₅OH.
37. The number of sigma bonds in benzene is:
a) 6
b) 3
c) 12
d) 9
View Answer
c) 12
Explanation: 6 C–C σ + 6 C–H σ = 12 σ bonds.
38. The catalyst used in hydrogenation of oils is:
a) V₂O₅
b) Ni
c) Pt
d) Fe
View Answer
b) Ni
Explanation: Vegetable oil + H₂ → Vanaspati ghee (Ni catalyst).
39. The greenhouse gas is:
a) O₂
b) N₂
c) CO₂
d) Ar
View Answer
c) CO₂
Explanation: Traps infrared radiation.
40. The hardest substance known is:
a) Graphite
b) Diamond
c) Fullerene
d) Glass
View Answer
b) Diamond
Explanation: 3D network of C–C covalent bonds.
41. The monomer of natural rubber is:
a) Isoprene
b) Styrene
c) Neoprene
d) Butadiene
View Answer
a) Isoprene
Explanation: [–CH₂–C(CH₃)=CH–CH₂–]ₙ.
42. The chemical name of baking soda is:
a) Na₂CO₃
b) NaHCO₃
c) CaCO₃
d) NaCl
View Answer
b) NaHCO₃
Explanation: Sodium hydrogen carbonate.
43. The pH of pure water at 25°C is:
a) 0
b) 7
c) 14
d) 1
View Answer
b) 7
Explanation: [H⁺] = [OH⁻] = 10⁻⁷ M → pH = 7.
44. The indicator used in weak acid–strong base titration is:
a) Methyl orange
b) Phenolphthalein
c) Litmus
d) Bromothymol blue
View Answer
b) Phenolphthalein
Explanation: Color change at pH 8.2–10.
45. The hybridization in BF₃ is:
a) sp
b) sp²
c) sp³
d) sp³d
View Answer
b) sp²
Explanation: Trigonal planar → sp² hybridization.
46. The strongest bond is:
a) Ionic
b) Covalent
c) Metallic
d) Hydrogen
View Answer
b) Covalent
Explanation: Bond energy highest in covalent bonds (e.g., C≡C).
47. The geometry of NH₃ molecule is:
a) Linear
b) Trigonal planar
c) Pyramidal
d) Tetrahedral
View Answer
c) Pyramidal
Explanation: Due to lone pair, distorted tetrahedral.
48. The chemical formula of plaster of Paris is:
a) CaSO₄·2H₂O
b) CaSO₄·½H₂O
c) CaSO₄
d) CaCO₃
View Answer
b) CaSO₄·½H₂O
Explanation: (CaSO₄)₂·H₂O.
49. The monomer of Teflon is:
a) Vinyl chloride
b) Tetrafluoroethylene
c) Styrene
d) Acrylonitrile
View Answer
b) Tetrafluoroethylene
Explanation: CF₂=CF₂ → [–CF₂–CF₂–]ₙ.
50. The number of π bonds in ethyne (C₂H₂) is:
a) 1
b) 2
c) 3
d) 0
View Answer
b) 2
Explanation: H–C≡C–H → one σ and two π bonds between carbons.