Year :
2017
Title :
Chemistry
Exam :
WASSCE/WAEC MAY/JUNE
Paper 1 | Objectives
21 - 30 of 50 Questions
| # | Question | Ans |
|---|---|---|
| 21. |
Which of the following statements about endothermic reaction is correct? A. Activation energy is high B. A catalyst is required C. It occurs reversibly D. Heat energy is absorbed Detailed SolutionEndothermic reactions are those reactions which absorb energy from the surroundings and result in a net decrease in temperature. |
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| 22. |
A 0.1\(moldm^{-3}\) solution of sodium hydroxide was diluted with distilled water to 0.001\(moldm^{-3}\). What is the dilution factor? A. 1000.00 B. 100.00 C. 10.00 D. 0.01 Detailed SolutionDilution factor = \(\frac{molar conc. of diluted}{molar conc. of undiluted}\)= \(\frac{0.001}{0.1} = 0.01\) |
|
| 23. |
Graphite and Diamond are similar in that they A. have octahedral shape B. have same density C. form carbon(IV) oxide on combustion D. conduct electricity Detailed SolutionA diamond is pure carbon. Graphite is pure carbon. Both will burn to form carbon dioxide. |
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| 24. |
In a saturated solution at a given temperature, the undissolved solutes are in equilibrium with A. the solvent B. dissolved solute particles C. the saturated solution D. insoluble solute particles Detailed SolutionA solution that is in equilibrium with undissolved solute is said to be saturated. |
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| 25. |
The number of atoms present in 2.5moles of a triatomic gas is equivalent to [1mole = \(6.02\times 10^{23}\)] A. \(2.5\times 10^{23}\) B. \(1.5\times 10^{23}\) C. \(1.5\times 10^{24}\) D. \(2.5\times 10^{24}\) Detailed Solution1 mole = \(6.02 \times 10^{23}\)2.5 moles = \(6.02 \times 10^{23} \times 2.5\) = \(15.05 \times 10^{23} = 1.505 \times 10^{24}\) \(\approxeq 1.5 \times 10^{24}\) |
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| 26. |
When Magnesium reacts with oxygen, heat is A. absorbed and the reaction is endothermic B. evolved and the reaction is endothermic C. evolved and the reaction is exothermic D. absorbed and the reaction is exothermic Detailed SolutionThe Magnesium actually reacts with oxygen in the air, is burnt and produces a bright light. The bright light emits a lot of heat so the reaction is exothermic. |
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| 27. |
Which of the following gases is not acidic? A. \(SO_{3}\) B. \(NO_{2}\) C. \(Co_{2}\) D. CO Detailed SolutionThe compound CO is treated as a neutral oxide, though in truth, it is slightly acidic. Regardless of this, within the options supplied, CO is the best option available. |
|
| 28. |
A hydrocarbon contained 14.3% hydrogen. The empirical formula for the hydrocarbon is [H= 1.0, C= 12.0] A. \(CH\) B. \(CH_{2}\) C. \(CH_{3}\) D. \(CH_{4}\) Detailed SolutionThe percentage of Carbon in the compound is (100 - 14.3)% = 85.7%C : H \(\frac{85.7}{12.0} : \frac{14.3}{1.0}\) \( 7.14 : 14.3\) \(\frac{7.14}{7.14} : \frac{14.3}{7.14}\) \(\approxeq 1 : 2\) Therefore, the empirical formula is \(CH_{2}\). |
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| 29. |
Which of the following statements is NOT a chemical property of an acid? A. Evolution of ammonia when heated with ammonium salts B. Evolution of carbon dioxide gas when added to a trioxocarbonate (IV) salt C. Formation of salt and water with alkalis D. Formation of salt and hydrogen gas with reactive metals Detailed SolutionAmmonium salts react with bases to release ammonia and not with acids. |
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| 30. |
Halogens generally react with metals to form A. alkalis B. acids C. bases D. salts Detailed SolutionThe word "halogen" is a Greek word meaning salt former, because they form salts when they react with metals eg NaCl. |
| 21. |
Which of the following statements about endothermic reaction is correct? A. Activation energy is high B. A catalyst is required C. It occurs reversibly D. Heat energy is absorbed Detailed SolutionEndothermic reactions are those reactions which absorb energy from the surroundings and result in a net decrease in temperature. |
|
| 22. |
A 0.1\(moldm^{-3}\) solution of sodium hydroxide was diluted with distilled water to 0.001\(moldm^{-3}\). What is the dilution factor? A. 1000.00 B. 100.00 C. 10.00 D. 0.01 Detailed SolutionDilution factor = \(\frac{molar conc. of diluted}{molar conc. of undiluted}\)= \(\frac{0.001}{0.1} = 0.01\) |
|
| 23. |
Graphite and Diamond are similar in that they A. have octahedral shape B. have same density C. form carbon(IV) oxide on combustion D. conduct electricity Detailed SolutionA diamond is pure carbon. Graphite is pure carbon. Both will burn to form carbon dioxide. |
|
| 24. |
In a saturated solution at a given temperature, the undissolved solutes are in equilibrium with A. the solvent B. dissolved solute particles C. the saturated solution D. insoluble solute particles Detailed SolutionA solution that is in equilibrium with undissolved solute is said to be saturated. |
|
| 25. |
The number of atoms present in 2.5moles of a triatomic gas is equivalent to [1mole = \(6.02\times 10^{23}\)] A. \(2.5\times 10^{23}\) B. \(1.5\times 10^{23}\) C. \(1.5\times 10^{24}\) D. \(2.5\times 10^{24}\) Detailed Solution1 mole = \(6.02 \times 10^{23}\)2.5 moles = \(6.02 \times 10^{23} \times 2.5\) = \(15.05 \times 10^{23} = 1.505 \times 10^{24}\) \(\approxeq 1.5 \times 10^{24}\) |
| 26. |
When Magnesium reacts with oxygen, heat is A. absorbed and the reaction is endothermic B. evolved and the reaction is endothermic C. evolved and the reaction is exothermic D. absorbed and the reaction is exothermic Detailed SolutionThe Magnesium actually reacts with oxygen in the air, is burnt and produces a bright light. The bright light emits a lot of heat so the reaction is exothermic. |
|
| 27. |
Which of the following gases is not acidic? A. \(SO_{3}\) B. \(NO_{2}\) C. \(Co_{2}\) D. CO Detailed SolutionThe compound CO is treated as a neutral oxide, though in truth, it is slightly acidic. Regardless of this, within the options supplied, CO is the best option available. |
|
| 28. |
A hydrocarbon contained 14.3% hydrogen. The empirical formula for the hydrocarbon is [H= 1.0, C= 12.0] A. \(CH\) B. \(CH_{2}\) C. \(CH_{3}\) D. \(CH_{4}\) Detailed SolutionThe percentage of Carbon in the compound is (100 - 14.3)% = 85.7%C : H \(\frac{85.7}{12.0} : \frac{14.3}{1.0}\) \( 7.14 : 14.3\) \(\frac{7.14}{7.14} : \frac{14.3}{7.14}\) \(\approxeq 1 : 2\) Therefore, the empirical formula is \(CH_{2}\). |
|
| 29. |
Which of the following statements is NOT a chemical property of an acid? A. Evolution of ammonia when heated with ammonium salts B. Evolution of carbon dioxide gas when added to a trioxocarbonate (IV) salt C. Formation of salt and water with alkalis D. Formation of salt and hydrogen gas with reactive metals Detailed SolutionAmmonium salts react with bases to release ammonia and not with acids. |
|
| 30. |
Halogens generally react with metals to form A. alkalis B. acids C. bases D. salts Detailed SolutionThe word "halogen" is a Greek word meaning salt former, because they form salts when they react with metals eg NaCl. |