Chemistry, 2016, WASSCE/WAEC MAY/JUNE, Exam, Paper 1 | Objectives

Paper Info

Year :

2016

Title :

Chemistry

Exam :

WASSCE/WAEC MAY/JUNE

Paper 1 | Objectives

31 - 40 of 50 Questions

#	Question	Ans
31.	On evaporation to dryness, 350³ of saturated solution of salt Z gave 55.5g of salt. What is the solubility of the salt? [Z = 101] A. 1.57 moldm^-3 B. 3.14 moldm^-3 C. 6.28 moldm^-3 D. 12.56 moldm^-3 Show Content Detailed Solution Saturated solution = 350³ mass of salt Z in saturated solution = 55.5g Number of moles of salt = \(\frac{55.5}{101}\) = 0.55mole 350³ of solution contains 0.55mole 1000cm³ will contain \(\frac{1000 \times 0.55}{350}\) = 1.57mol/dm³	A
32.	Which of the following salts when dissolved in water will form a solution that will change blue litmus to red? A. CH₃COONa B. NH₄Cl C. NaCl D. KCl	B
33.	Which of the following bonds are broken when ethanol is boiled? I. Covalent bonds II. Ionic bonds III. Hydrogen bonds A. I only B. II only C. III only D. I, II, III	C
34.	A compound with molecular formula CH₂O₂ is A. A Carbohydrate B. A Carboxylic acid C. An alkanol D. An ester	B
35.	The quality of electricity required to discharge 1 mole of univalent ion is A. 9600C B. 48250C C. 96500C D. 193000C	C
36.	Chlorine water is used as a bleaching agent because it is A. An acidic solution B. An alkaline solution C. An oxidizing agent D. A reducing agent	C
37.	Which of the following substances is a non-electrolyte? A. H₂SO₄ B. CH₃COOH C. C₆H₁₂O₆ D. NH₄Cl	C
38.	The oxidation number of sulphur is +4 in A. Na₂S>₂O₃ B. H₂SO₃ C. H₂SO₄ D. SO₃	B
39.	Consider the following ionic equation: Cr₂O₇^2- + 14H⁺ + ne^- \(\to\) 2Cr³⁺ + 7H₂O. The value of n in the equation is_______? A. 7 B. 6 C. 3 D. 2	B
40.	Consider the following half-cell reactions. Al_(s) \(\to\) Al³⁺_(aq) + 3e^- Cu²⁺_(aq) + 2e^- \(\to\) Cu_(s) The overall equation for the reaction is A. Al_(s) + Cu²⁺_(aq) \(\to\) Al³⁺_(aq) + Cu_(s) B. 2Al_(s) + Cu²⁺_(aq) \(\to\) 2Al_(aq) + Cu_(s) C. 2Al_(s) + 3Cu²⁺_(aq) \(\to\) 3Cu_(s) + 2Al³⁺_(aq) D. 3Al_(s) + 2Cu²⁺_(aq) \(\to\) Cu_(s) + 3Al³⁺_(aq) Show Content Detailed Solution Al_(s) \(\to\) Al³⁺_(aq) + 3e^- ______(i) Cu²⁺_(aq) + 2e^- \(\to\) Cu_(s) ________(ii) To balance the electrons, multiply equation (i) by 2 and equation (ii) by 3 and then add the resulting equations 2Al_(s) \(\to\)2Al³⁺_(aq) + 3e^- 3cu²⁺_(aq) + 6e^- \(\to\)3Cu_(s) 2Al_(s) + 3Cu²⁺	C

31.	On evaporation to dryness, 350³ of saturated solution of salt Z gave 55.5g of salt. What is the solubility of the salt? [Z = 101] A. 1.57 moldm^-3 B. 3.14 moldm^-3 C. 6.28 moldm^-3 D. 12.56 moldm^-3 Show Content Detailed Solution Saturated solution = 350³ mass of salt Z in saturated solution = 55.5g Number of moles of salt = \(\frac{55.5}{101}\) = 0.55mole 350³ of solution contains 0.55mole 1000cm³ will contain \(\frac{1000 \times 0.55}{350}\) = 1.57mol/dm³	A
32.	Which of the following salts when dissolved in water will form a solution that will change blue litmus to red? A. CH₃COONa B. NH₄Cl C. NaCl D. KCl	B
33.	Which of the following bonds are broken when ethanol is boiled? I. Covalent bonds II. Ionic bonds III. Hydrogen bonds A. I only B. II only C. III only D. I, II, III	C
34.	A compound with molecular formula CH₂O₂ is A. A Carbohydrate B. A Carboxylic acid C. An alkanol D. An ester	B
35.	The quality of electricity required to discharge 1 mole of univalent ion is A. 9600C B. 48250C C. 96500C D. 193000C	C

36.	Chlorine water is used as a bleaching agent because it is A. An acidic solution B. An alkaline solution C. An oxidizing agent D. A reducing agent	C
37.	Which of the following substances is a non-electrolyte? A. H₂SO₄ B. CH₃COOH C. C₆H₁₂O₆ D. NH₄Cl	C
38.	The oxidation number of sulphur is +4 in A. Na₂S>₂O₃ B. H₂SO₃ C. H₂SO₄ D. SO₃	B
39.	Consider the following ionic equation: Cr₂O₇^2- + 14H⁺ + ne^- \(\to\) 2Cr³⁺ + 7H₂O. The value of n in the equation is_______? A. 7 B. 6 C. 3 D. 2	B
40.	Consider the following half-cell reactions. Al_(s) \(\to\) Al³⁺_(aq) + 3e^- Cu²⁺_(aq) + 2e^- \(\to\) Cu_(s) The overall equation for the reaction is A. Al_(s) + Cu²⁺_(aq) \(\to\) Al³⁺_(aq) + Cu_(s) B. 2Al_(s) + Cu²⁺_(aq) \(\to\) 2Al_(aq) + Cu_(s) C. 2Al_(s) + 3Cu²⁺_(aq) \(\to\) 3Cu_(s) + 2Al³⁺_(aq) D. 3Al_(s) + 2Cu²⁺_(aq) \(\to\) Cu_(s) + 3Al³⁺_(aq) Show Content Detailed Solution Al_(s) \(\to\) Al³⁺_(aq) + 3e^- ______(i) Cu²⁺_(aq) + 2e^- \(\to\) Cu_(s) ________(ii) To balance the electrons, multiply equation (i) by 2 and equation (ii) by 3 and then add the resulting equations 2Al_(s) \(\to\)2Al³⁺_(aq) + 3e^- 3cu²⁺_(aq) + 6e^- \(\to\)3Cu_(s) 2Al_(s) + 3Cu²⁺	C