PES SS 3 Chemistry Mock 1 Exam 2025-26
  • 1. The periodic table is an arrangement of elements according to their?
A) Oxidation number
B) Number of electrons
C) Atomic number
D) Mass number
  • 2. Which of the following metals reacts slowly with cold water?
A) Calcium
B) Silver
C) Potassium
D) Iron
  • 3. The IUPAC name of the compound represented by the structure below is ?
A) 2-chloro but-diene.
B) 3 -chloro but -1.3-diene.
C) 2- chloro but-I ,3-diene.
D) But-1,3-chlorodiene.
  • 4. Group VIl elements in their combined states are called __________
A) Halides
B) Anions
C) Cations
D) Halogens
  • 5. The oxidation state of chlorine in NaClO3 is ___
A) +1
B) +5
C) +3
D) +6
  • 6. An alkanol containing 60% carbon by mass would have a molecular formula [H=1.0. C-12.0, O= 16.0]
A) CH3OH
B) C2H5OH
C) C3H7OH
D) C4H9OH
  • 7. Which of the following statements is correct for a reaction at equilibrium?
A) The reaction has gone to completion
B) The rates of the forward and backward reactions are equal
C) The amount of product equals the amount of reactants
D) All reactions cease to occur
  • 8. The bond between NH3 and H+ in NH4+ is ____
A) Hydrogen
B) Electrovalent
C) Dative
D) Covalent
  • 9. "Electrons always occupy the lowest empty energy level" is a statement of
A) Pauli's exclusion principle
B) Hund's rule
C) Afbau's principle
D) Periodic law
  • 10. Which of the following metals does not react with water to produce hydrogen?
A) Potassium
B) Zinc
C) Sodium
D) Copper
  • 11. The metallic bond in magnesium is stronger than that in calcium because magnesium has a
A) Larger Atomic Size
B) Smaller Atomic size
C) Greater number of valence electrons
D) Lower melting point
  • 12. Which of the following processes is not exhibited by atoms in order to attain more stable electron configuration?
A) Gaining of electrons
B) Losing of electrons
C) Sharing electrons
D) Hybridization of Orbitals
  • 13. An example of a biodegradable pollutant is _______
A) Hydrogen Sulphide
B) Carbon (II) oxide
C) Sewage
D) Plastic
  • 14. A factor that is considered most important when siting a chemical industry is __________
A) Favourable climate condition
B) Availability of storage facilities
C) Nearness to raw materials
D) Nearness to industrial establishment
  • 15. The following molecules have double covalent bonds between two atoms except _____
A) Carbon (IV) oxide
B) Oxygen
C) Ethene
D) Water
  • 16. The type of isomerism exhibited by cis and trans isomers is _______
A) Functional
B) Optical
C) Geometrical
D) Positional
  • 17. An organic compound contains 72% carbon, 12% hydrogen and 16% oxygen by mass. What is the empirical formula of the compound?

    [ H = 1.0. C = 12.0, O = 16.0 ]
A) C3H8O
B) C6H12O
C) C12H12O11
D) C6H12O2
  • 18. In a mixture of gases which do not react chemically together, the pressure of the individual gas is _______
A) partial pressure
B) Atmospheric pressure
C) Total pressure
D) Vapour pressure
  • 19. Which of the following methods is NOT used  for the separation of mixtures?
A) Distillation
B) Electrolysis
C) Chromatography
D) Crystalization
  • 20. The group to which elements belong in the periodic table is determined by the number of _______
A) Valence shells
B) Core electrons
C) Electrons
D) Valence electrons
  • 21. If the value of ΔH is positive for a reaction, it means that the reaction is?
A) Endothermic
B) Exothermic
C) Spontaneous
D) Slow
  • 22. Stoichiometry is based on the law of ______
A) conservation of energy
B) conservation of mass
C) Multiple proportion
D) Constant composition
  • 23. How many moles of carbon(iv)oxide contains 16.0g of oxygen?

    [ C = 12.0, O = 16.0 ]
A) 0.25 mol
B) 0.20 mol
C) 0.40 mol
D) 0.50 mol
  • 24. Calcium and magnesium belong to the same group of the periodic table because both ____
A) form cations
B) are metals
C) have same number of valence electrons
D) form colourless salts
  • 25. When an equilibrium is established between dissolved and undissolved solutes, the solution is said to be _____
A) Diluted
B) Saturated
C) Concentrated
D) Unsaturated
  • 26. The region around the nucleus where electrons can be located is called _____
A) A field
B) An orbital
C) A spectra
D) A quanta
  • 27. Electrovalent compounds normally ------------
A) Conduct electricity in its solid state
B) Have low boiling points
C) Dissolve in polar solvent
D) Have mobile electrons
  • 28. How many coulombs of electricity would liberate 1.08g of Ag from a solution of silver salt?

    [Ag = 108.0; 1F = 96500 C]
A) 965 C
B) 96500 C
C) 9650 C
D) 9.65 C
  • 29. The process by which alkanoic acid reacts reversibly with alkanols is known as ____
A) esterification
B) Carboxylation
C) Halogenation
D) Saponification
  • 30. Which of the following raw materials is used in the plastic industry?
A) Hydrogen
B) Sulphur
C) Ethene
D) Methane
  • 31. Which of the following organic compounds can undergo both addition and substitution reactions?
A) Benzene
B) Pentane
C) Propane
D) Hexane
  • 32. Pauli exclusion principle is related to
A) the filling of degenerated orbitals
B) quantum numbers of electrons
C) filling the orbitals with lower energy first
D) quantity of electrons in the valence shell
  • 33. The separation of Nitrogen from oxygen using fractional distillation of air is possible because
A) they belong to the same period
B) of the difference in their boiling points
C) oxygen is more reactive than nitrogen
D) nitrogen is less dense than oxygen
  • 34. What is the solubility of a salt if 0.4g of it is obtained on evaporating 200cm3 of its saturated solution to dryness?
A) 0.08gdm−3
B) 80.00gdm−3
C) 2.00gdm−3
D) 8.00gdm−3
  • 35. An acidic salt has
A) hydrogen atoms in its aqueous solution
B) double anions in its aqueous solution
C) hydrogen ions in its aqueous solution
D) a single cation in its aqueous solution
  • 36. A reaction is endothermic if the
A) heat of formation of reactants exceeds heat of formation of products
B) bond forming energy exceeds bond breaking energy
C) enthalpy change is negative
D) reaction vessel feels cool during the reaction
  • 37. In which of the following compounds does hydrogen form ionic compounds?
A) NH3
B) HCl
C) NaH
D) CH4
  • 38. An organic compound has the empirical formula CH2 . If its molar mass is 42gmol−1 , what is its molecular formula? (C = 12.0, H = 1.0)
A) C3H4
B) C2H4
C) C3H6
D) C4H8
  • 39. The mass of one mole of (NH4)_2CO3 is [O=16.0, N=14.0, C=12.0, H=1.0]
A) 66.0g
B) 96.0g
C) 80.0g
D) 76.0g
  • 40. The reason for the decrease in the atomic size of elements across a period is that
A) nuclear charge decreases while the outermost electrons are drawn closer to the nucleus
B) nuclear charge decreases while the distance of the valence shell from the nucleus is increasing
C) valence electrons increase across the period while the valence shell remains constant
D) nuclear charge increases while the outermost electrons are drawn closer to the nucleus
  • 41. The oxidation number of nitrogen in Pb(NO3)_2 is
A) +2
B) +3
C) +5
D) +4
  • 42. Which of the following metals has the strongest metallic bond?
A) K
B) Na
C) Mg
D) Al
  • 43. The use of diamond in abrasives is due to its
A) durability
B) hardness
C) octahedral shape
D) high melting point
  • 44. A 0.1moldm−3 solution of sodium hydroxide was diluted with distilled water to 0.001moldm−3 . What is the dilution factor?
A) 10.00
B) 100.00
C) 1000.00
D) 0.01
  • 45. Graphite and Diamond are similar in that they
A) form carbon(IV) oxide on combustion
B) have octahedral shape
C) have same density
D) conduct electricity
  • 46. Consider the following reaction equation: Br2 + 2KI → 2KBr + I2 . Bromine is acting as
A) a reducing agent
B) an oxidizing agent
C) an acid
D) a base
  • 47. What is the mass of solute in 500cm3 of 0.005moldm−3 H2SO4 ? ( H = 1, S = 32.0, O=16.0)
A) 0.245g
B) 0.049g
C) 0.0245g
D) 0.490g
  • 48. At what temperature does the solubility of KNO3 equal that of NaNO3 ?
A) 40°C
B) 30°C
C) 0°C
D) 20°C
  • 49. The preferential discharge of ions during electrolysis is influenced by the
A) electrolytic reactions
B) electrochemical reactions
C) nature of the electrode
D) mechanism of electrolysis
  • 50. The valence electrons of Mg are in the
A) 1s orbital
B) 2s orbital
C) 3s orbital
D) 2px
  • 51. The most suitable substance for putting out petrol fire is
A) fire blanket
B) water
C) carbon(IV) oxide
D) sand
  • 52. Which of the following statements is NOT a chemical property of an acid?
A) Evolution of carbon dioxide gas when added to a trioxocarbonate (IV) salt
B) Formation of salt and water with alkalis
C) Evolution of ammonia when heated with ammonium salts
D) Formation of salt and hydrogen gas with reactive metals
  • 53. The number of Hydrogen ions in 1.0dm3 of 0.02moldm−3 tetraoxosulphate (VI) acid is ________________ [NA=6.02×1023]
A) 2.4 × 1022
B) 1.2 × 1022
C) 1.2 × 1023
D) 2.4 × 1023
  • 54. When water was added to a white anhydrous substance X, the colour changed to blue. X is
A) FeSO4
B) PbSO4
C) CuSO4
D) Na2SO4
  • 55. The following factors would contribute to environmental pollution except
A) manufacture of cement
B) combustion
C) photosynthesis
D) production of ammonia
  • 56. Consider the following reaction equation: 2HCl + Ca(OH)_2 → CaCl2 + H2O . What is the volume of 0.1 moldm−3 HCl that would completely neutralize 25cm3 of 0.3moldm−3 Ca(OH)_2 ?
A) 30cm3
B) 75cm3
C) 150cm3
D) 25cm3
  • 57. One of the criteria for confirming the purity of benzene is to determine its
A) mass
B) heat capacity
C) boiling point
D) colour
  • 58. When chlorine is passed through a sample of water, the pH of the water sample would be
A) = 7
B) < 7
C) > 7
D) 0
  • 59. Which of the following properties would not influence electrovalent bond formation?
A) Catalytic ability
B) Electron Affinity
C) Electronegativity
D) Ionization potential
  • 60. Particles in a solid exhibit
A) vibrational and random motion
B) vibrational motion
C) random and translational motion
D) vibrational and translational motion
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