PES SS 3 Chemistry Obj Mock 1 Exam 2026-27

1. The hydrolysis of proteins by diluting mineral acids produces

A) fatty acids
B) amino acids
C) glucose
D) sucrose

2. Which of the following oxide causes acid rain?

A) H₂O₂
B) NO
C) CO
D) NO₂

3. The ratio of carbon atoms of hydrogen atoms in a hydrocarbon is 1:2. If its molecular mass is 56, what is its molecular formula?

A) C₄H₈
B) C₂H₄
C) CH₂
D) C₃H₆

4. What is the relative molecular mass of the compound below?

A) 59
B) 137
C) 136
D) 64

5. Cathodic protection of metals is based on

A) relative tendencies of oxidation
B) its electrical conductivity
C) nature of oxides formed
D) standard electrode potential of hydrogen

6. If humid air is polluted by chlorine discharged, the air can be restored by sprinkling

A) acidified FeSO₄
B) acidified KMnO₄
C) saturated NaCl(aq)
D) solid MnO₂

7. The alkanol represented by the structure above is

A) primary and dihydric
B) secondary and monohydric
C) tertiary and dihydric
D) secondary and dihydric

8. Which of the following pairs of compounds would form a precipitate when their aqueous solutions are mixed?

A) KCl and NaNO₃
B) K₂SO₄ and BaCl₂
C) NaCl and KNO₃
D) NH₄NO₃ and Na₂CO₃

9. Study the graphs below (I, II, III, IV) and use them to answer questions 9 to 11.

Which of the graphs illustrates the variation of the rate of evolution of a gas from a given length of magnesium ribbon (y-axis) with increase in the concentration of the acid added (x-axis)?

A) II
B) IV
C) I
D) III

10. Study the graphs below (I, II, III, IV) and use them to answer questions 9 to 11.

Which of the graphs illustrates the variation of the pH of a given volume of strong acid solution (y-axis) with the volume of strong base titrated against it (x-axis)?

A) I
B) III
C) IV
D) II

11. Study the graphs below (I, II, III, IV) and use them to answer questions 9 to 11.

Which of the graphs illustrates the variation of the solubility of a salt in water (y-axis) with increase in temperature (x-axis), if the dissolution process is exothermic?

A) IV
B) I
C) II
D) III

12. The formation of ethene from dehydration of ethanol can be described as

A) an addition reaction.
B) an elimination reaction.
C) an oxidation reaction.
D) a substitution reaction.

13. Which of the following gases is highly soluble in water at room temperature?

A) Carbon (IV) oxide
B) Nitrogen
C) Ammonia
D) Chlorine

14. A molecule of phosphorus is

A) a monoatomic.
B) a diatomic.
C) a tetraatomic.
D) a triatomic.

15. The most common method of preparing insoluble salts is by

A) decomposition.
B) filtration.
C) neutralization.
D) double decomposition.

16. What number of moles of oxygen would exert a pressure of 10 atm at 320K in an 8.2dm³ cylinder? [R=0.082 atm dm³mol⁻¹K⁻¹]

A) 1.56
B) 0.32
C) 3.13
D) 31.25

17. The basic property of salts used as drying agents is

A) low solubility.
B) efflorescence.
C) hygroscopy.
D) high melting point.

18. What would be observed when aqueous ammonia is added in drops and then in excess to a solution of copper (II) ions?

A) A blue precipitate is formed which is soluble in excess ammonia
B) A white precipitate is formed which is soluble in excess ammonia
C) A green precipitate is formed which is insoluble in excess ammonia
D) A brick red precipitate is produced which is insoluble in excess ammonia

19. When CuSO4(aq) is added to Pb(NO3)2(aq),

A) there would be no visible change.
B) a white precipitate would be formed.
C) a blue precipitate would be formed.
D) the resulting solution would become colourless.

20. Consider the structure below (a carbon chain with -OH, a C₂H₅ branch, and a C=O group). How many carbon atoms does the parent chain contain?

A) 3
B) 5
C) 2
D) 4

21. Under which conditions of pressure (P) and temperature (T) would the volume of an inflated balloon increase? When

A) T is decreased and P is increased
B) both T and P are decreased
C) T is increased and P is decreased
D) both T and P are increased

22. The collision between ideal gas molecules are considered to be perfectly elastic because

A) their average kinetic energy is variable.
B) they collide without losing energy.
C) they move randomly in straight lines.
D) the distance between them is large compared to their sizes.

23. Elements with high ionization energies would

A) lose electrons easily.
B) have high effective nuclear charges.
C) have low atomic numbers.
D) have large atomic radii.

24. Which of the following statements about Group VII elements is correct?

A) Their reactivity decreases down the group
B) They are present in the same physical state
C) They exist as monoatomic molecules
D) They are strong reducing agents

25. Consider the diagram below and use it to answer questions 25 and 26 (electrochemical cell with crystals A and B, A(aq)3+ and B(aq)2+).

Which of the following cell notations represent the diagram?

A) A/A3+//B2+/B
B) A3+/A//B/B2+
C) B/B2+//A/A3+
D) B2+/B//A/A3+

26. Consider the diagram below and use it to answer questions 25 and 26 (electrochemical cell with crystals A and B, A³⁺ (aq) and B²⁺ (aq).

Which of the following half reaction equations represent the reaction at the cathode?

A) A3+(aq)+3e⁻→A(s)
B) B2+(aq)+2e⁻→B(s)
C) B(s)→B2+(aq)+2e⁻
D) A(s)→A3+(aq)+3e⁻

27. The reactivity of fluorine is high because of

A) the availability of d-orbitals.
B) the strong F-F bond.
C) its high electronegativity.
D) the small size of the fluorine atom.

28. How many coulombs of electricity would liberate 1.08g of Ag from a solution of silver salt? [Ag=108.0; 1F=96500C]

A) 96500C
B) 965C
C) 9.65C
D) 9650C

29. The Bohr model of the atom proposed

A) electron shells.
B) the existence of the nucleus.
C) nucleons.
D) neutrons.

30. At 25°C, evaporation of a 100cm³ solution of K2CO₃ to dryness gave 14g of the salt. What is the solubility of K2CO₃ at 25°C? [K2CO3=138]

A) 0.101 mol dm⁻³
B) 1.01 mol dm⁻³
C) 10.0 mol dm⁻³
D) 0.01 mol dm⁻³

31. Student X titrated 25cm³ of Na₂CO₃ with 0.1mol dm⁻³ HCl, using methyl orange as indicator. Student Y carried out the same exercise but used phenolphthalein as indicator. Which of the following statements about the titration is true?

A) The titre value obtained by X is twice that of Y
B) The titre values obtained from the titrations are equal
C) The titre value obtained by Y is twice that of X
D) Hydrogen chloride gas was released in the reactions in both titrations

32. What is the concentration of a solution which contains 0.28g of potassium hydroxide in 100cm³ of solution? [KOH=56]

A) 0.05 mol dm⁻³
B) 0.50 mol dm⁻³
C) 0.01 mol dm⁻³
D) 0.10 mol dm⁻³

33. What is the empirical formula of a hydrocarbon containing 0.160 moles of carbon and 0.640 moles of hydrogen?

A) CH₄
B) CH₃
C) CH₂
D) C₂H₄

34. Which of the following species has the largest ionic radius?

A) Ca2+
B) Cl-
C) S2-
D) K+

35. Which of the following statements is correct about ionization energy? It

A) decreases down the group
B) results in the formation of an anion
C) decreases across the periods
D) causes metallic nuclei to disintegrate

36. Potassium trioxonitrate (V) can be obtained from its solution by

A) evaporation.
B) distillation.
C) crystallization.
D) filtration.

37. An element, Q, contains 69.0% of 63Q and 31% of 65Q. What is the relative atomic mass of Q?

A) 69.0
B) 65.0
C) 63.6
D) 63.0

38. The following ions have the same electron configuration except ____

A) Al³⁺
B) Mg²⁺
C) O^2-
D) Cl⁻

39. The region around the nucleus where electrons can be located is called

A) an orbital.
B) a spectra.
C) a field.
D) a quanta.

40. Protons and electrons are called fundamental particles because they

A) are found in all matter.
B) have different charges.
C) are the lightest particles.
D) are indivisible.

41. Consider the following energy profile diagram (Potential Energy vs Reaction Co-ordinates) and use it to answer questions 41 to 43.

The activation energy of the reaction is

A) EC
B) ED
C) EA
D) EB

42. Consider the following energy profile diagram (Potential Energy vs Reaction Co-ordinates) and use it to answer questions 41 to 43.

The enthalpy change of the reaction is

A) EB
B) ED
C) EA
D) EC

43. Consider the following energy profile diagram (Potential Energy vs Reaction Co-ordinates) and use it to answer questions 41 to 43.

The energy profile diagram illustrates

A) a spontaneous reaction.
B) an exothermic reaction.
C) a redox reaction.
D) an endothermic reaction.

44. How many molecules of oxygen would occupy a volume of 2.24cm³ at s.t.p.?
[Molar volume at s.t.p.=22,400cm³;
Avogadro's number = 6.02×10²³]

A) 3.01×10²⁰
B) 3.01×10²¹
C) 6.02×10¹⁹
D) 6.02×10²⁷

45. The relationship between x, y and z is

A) xy<z.
B) x>y>z.
C) x=y=z.
D) x<z<y.

46. Which of the following pairs of molecules form hydrogen bonds?

A) H₂S and CH₄
B) C₂H₅OH and CH₃OH
C) NH₃ and SO₂
D) C₆H₆ and Br₂

47. Which of the following statements about elements in Group VII is correct?

A) Cl₂ will oxidize I⁻
B) I₂ is a stronger oxidizing agent than F₂
C) F₂ has the least tendency to be reduced
D) Br will oxidize Cl⁻

48. Electrovalent compounds normally

A) have low boiling points.
B) conduct electricity in the solid state.
C) dissolve in polar solvents.
D) have mobile electrons.

49. A coordinate covalent bond could be formed between

A) H+ and AlCl3.
B) BCl3 and NH3.
C) NH3 and PCl3.
D) BCl3 and AlCl3.

50. Which of the following scientists discovered the electron?

A) Joseph J. Thompson
B) Amedeo Avogadro
C) Ernest Rutherford
D) James Chadwick

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