SS 2 Chemistry Third Term Examination

THIRD TERM

Examination Malpractices May Lead to a Repeat of the Subject or Suspensions. Don’t Be Involved.

SUBJECT: CHEMISTRY

CLASS: S.S.S TWO

DURATION: 2 HR

OBJECTIVE QUESTIONS

1. Water is temporarily hard because it contains
   • a. CaSO₄
   • b. MgSO₄
   • c. Chlorine
   • d. Ca(HCO₃)₂
2. The following are characteristics of colloids except
   • a. Tyndall effect on light beam
   • b. Solid phase is removed by dialysis
   • c. Colloidal particles are larger than that of suspensions
   • d. Colloidal particles are separated using parchment membranes
3. One of these is not a water pollutant
   • a. Petroleum
   • b. Domestic liquid and solid waste
   • c. Industrial effluents
   • d. Biodegradable chemicals
4. 144 g of KCl dissolved in 1 dm³ of water at 90°C in the presence of excess crystals of KCl. Calculate the solubility of KCl at this temperature. (K = 39, Cl = 35.5)
   • a. 0.89 mol dm⁻³
   • b. 1.93 mol dm⁻³
   • c. 1.75 mol dm⁻³
   • d. 1.5 mol dm⁻³
5. What is the volume occupied by 2 moles of ammonia at S.T.P?
   • a. 44.8 dm³
   • b. 22.4 dm³
   • c. 11.2 dm³
   • d. 5.6 dm³
6. Consider the neutralization reaction represented by the following equation: Na₂CO₃ + 2HNO₃ → 2NaNO₃ + H₂O + CO₂. The stoichiometric ratio of acid to base is
   • a. 2:2
   • b. 2:1
   • c. 1:2
   • d. 1:1
7. The shape of the water molecule is
   • a. Angular
   • b. Tetrahedral
   • c. Pyramidal
   • d. Linear
8. The volume occupied by 0.4 g of hydrogen gas at S.T.P. is (H = 1.00, Molar volume at S.T.P = 22.4 dm³)
   • a. 2.24 dm³
   • b. 4.48 dm³
   • c. 22.4 dm³
   • d. 8.96 dm³
9. Which of the following will not decolourise bromine water?
   • a. C₂H₆
   • b. C₂H₄
   • c. C₃H₄
   • d. C₃H₆
10. The gas that can be best collected by downward displacement of air
    • a. Chlorine
    • b. Carbon (IV) oxide
    • c. Sulphur (IV) oxide
    • d. Ammonia
11. Which of the following properties of elements decreases generally across a period in the periodic table?
    • a. Electronegativity
    • b. Electron affinity
    • c. Atomic radius
    • d. Ionization energy
12. If the electron configuration of an element is 1s²2s²2p⁶3s²3p⁶, it shows that it is a:
    • a. Group II element
    • b. Noble gas
    • c. Group V element
    • d. Group II element
13. Cr₂O₇²⁻ + 14H⁺ + xe⁻ → 2Cr³⁺ + 7H₂O. The number of moles (x) of electrons in the above half-cell equation is:
    • a. 2
    • b. 4
    • c. 7
    • d. 6
14. The volume occupied by 0.4 g of hydrogen gas at S.T.P. is (H = 1.00, molar volume at S.T.P = 22.4 dm³)
    • a. 2.24 dm³
    • b. 4.48 dm³
    • c. 22.4 dm³
    • d. 8.96 dm³
15. A measure of the degree of disorderliness in a chemical system is known as:
    • a. Enthalpy
    • b. Free energy
    • c. Entropy
    • d. Activation energy
16. H₂(g) + X₂(g) → 2HX(g), ΔH = positive. In the above reaction, a decrease in temperature will:
    • a. Decrease the concentration of HX
    • b. Favour the forward reaction
    • c. Favour the yield HX
    • d. Have no effect on the equilibrium position
17. 3Fe(s) + 4H₂O(g) ⇌ Fe₃O₄ + 4H₂(g). The equilibrium constant K of the reaction above is represented as:
    • a. [H₂]⁴/[H₂O]⁴
    • b. [Fe]³[H₂O]⁴/[Fe₃O₄][H₂]⁴
    • c. [Fe₃O₄][H₂]⁴/[Fe]³[H₂O]⁴
    • d. [H₂]⁴/[H₂]⁴
18. What is the quantity of electricity produced when a current of 0.5 A is passed for 5 hours 45 minutes (F = 96500)?
    • a. 0.11F
    • b. 0.22F
    • c. 0.12F
    • d. 1.1F
19. The oxidation number of phosphorus in PO₄³⁻ is:
    • a. +1
    • b. +3
    • c. +4
    • d. +5
20. Compounds that exist in two or more different structural forms which also differ in chemical or/and physical properties but possess the same molecular formula are said to exhibit:
    • a. Isotopy
    • b. Isomerism
    • c. Polymerism
    • d. Allotropy
21. Consider the reaction represented by the following equation: H-C≡C-H H₂ → X H₂ → Y; X and Y respectively are:
    • a. Ethene and ethane
    • b. Ethane and ethene
    • c. Ethyne and ethane
    • d. Ethane and propene
22. Compound N reacts with sodium metal to produce a gas that gives a “pop” sound with a burning splint. N also reacts with ethanol to give a sweet-smelling liquid. Compound N is an:
    • a. Alkanol
    • b. Alkanoate
    • c. Alkane
    • d. Alkanoic acid
23. A solution of sodium trioxocarbonate (IV) contains 10.6 g in 250 cm³ of solution. Calculate the concentration of the solution. [Na₂CO₃ = 106.0]
    • a. 0.4 mol dm⁻³
    • b. 1.0 mol dm⁻³
    • c. 10.6 mol dm⁻³
    • d. 25.0 mol dm⁻³
24. The IUPAC name of the compound:
    Copy code

    CH₃ CH₃
| |
CH₃-CH-CH-CH₃

    • a. 2,3-dimethylpent-2,3-one
    • b. 3,4-dimethylpent-2-one
    • c. 2,3-dimethylbutane
    • d. 3,4-dimethylpentene
25. The alkanoate CH₃CH₂COOC₂H₅ is the product of the reaction between:
    • a. Ethanoic acid and ethanol
    • b. Ethanoic acid and propanol
    • c. Propanoic acid and ethanol
    • d. Propanoic acid and propanol
26. Filling the burette for titration involves these except:
    • a. Wash with water
    • b. Rinse with acid
    • c. Eject air bubbles
    • d. Read at eye level
27. The change from the degree of unsaturation to saturation is called ___________ reaction.
    • a. Substitution
    • b. Addition
    • c. Saturation
    • d. Fermentation

THEORY QUESTIONS

1. Explain the term “activation energy” and describe its significance in chemical reactions.
2. Given the following reaction: 2KClO3(s)→2KCl(s)+3O2(g)2KClO₃ (s) \rightarrow 2KCl (s) + 3O₂ (g)2KClO3​(s)→2KCl(s)+3O2​(g)
   • (a) Calculate the volume of O₂ gas produced at S.T.P. when 12.25 g of KClO₃ is heated (K = 39, Cl = 35.5, O = 16).
   • (b) Describe how you would confirm the gas produced is oxygen.
3. Differentiate between a “molecular formula” and an “empirical formula” with examples.
4. Explain the principle behind the separation of components in chromatography and mention one practical application of this technique.
5. A compound contains 40% carbon, 6.7% hydrogen, and 53.3% oxygen. Determine its empirical formula.
6. Write balanced chemical equations for the following reactions:
   • (a) Sodium reacting with water.
   • (b) Hydrochloric acid reacting with sodium hydroxide.
   • (c) Ethene reacting with bromine water.
7. Discuss the importance of the pH scale in chemistry. Provide an example of a substance for each of the following pH ranges: acidic, neutral, and basic.
8. Describe the process of electrolysis and its application in the extraction of metals, using aluminium as an example.
9. Explain the concept of “catalysis” and distinguish between homogeneous and heterogeneous catalysis with examples.
10. Calculate the enthalpy change (ΔH) for the following reaction, given the bond dissociation energies: H2(g)+Cl2(g)→2HCl(g)H₂ (g) + Cl₂ (g) \rightarrow 2HCl (g)H2​(g)+Cl2​(g)→2HCl(g)
    • Bond dissociation energies: H-H = 436 kJ/mol, Cl-Cl = 243 kJ/mol, H-Cl = 431 kJ/mol.

END OF EXAMINATION