Year :
2020
Title :
Chemistry
Exam :
WASSCE/WAEC MAY/JUNE
Paper 1 | Objectives
1 - 10 of 49 Questions
| # | Question | Ans |
|---|---|---|
| 1. |
Which of the following substances is an example of a fine chemical? A. Sodium hydroxide B. Hydrochloric acid C. Ethylene D. Ammonia Detailed Solution- Fine chemicals are complex, single, pure chemical substances, produced in limited quantities.- Heavy chemicals are produced and handled in large lots and are often in a crude state. - Some examples of heavy chemicals are ammonia, sulfuric acid, and sodium hydroxide. |
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| 2. |
The IUPAC name of the compound represented by the structure below is ? A. 2- chloro but-I ,3-diene. B. But-1,3-chlorodiene. C. 2-chloro but-diene. D. 3 -chloro but -1.3-diene. |
A |
| 3. |
Which or the following substances is a polypeptide? A. Starch B. Glycogen C. Protein D. Fats Detailed Solution- A polypeptide is defined as a polymer of amino acids joined together by peptide bonds.- Proteins are polymers of amino acids. |
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| 4. |
Which or the following products could be formed during incomplete combustion of a hydrocarbon.i.Carbon ii. Hydrogen III. Carbon (Il) oxide A. I only B. I and II only C. I and III only D. II and III only Detailed SolutionIncomplete combustion occurs when the supply of air or oxygen is poor. Water is still produced, but carbon monoxide and carbon are produced instead of carbon dioxide. The carbon is released as soot. |
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| 5. |
What quantity of electrons is lost when one mole of iron (II) ions is oxidized to iron (III) ? A. 0 mole B. 3 moles C. I mole D. 2 moles Detailed SolutionFe\(^2^+\) → Fe\(^3^+\)The pale green Fe2+ is oxidized to orange Fe3+ because it loses an electron. |
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| 6. |
What is the mass of silver deposited when 24,125 C of electricity is passed through a solution or silver salt.[Ag = 108, IF = 96,500 C ] A. 432g B. 108g C. 54g D. 27g Detailed SolutionAg + e → Ag1 mole of Ag+ = 108 i.e 108 X 1 X 96500 But, 24,125C will produce ( 108 X 24,125 ) / ( 1 X 96500 ) Ag = 27g |
|
| 7. |
Equal masses of calcium trioxocarbonate(iv) were added to dilute hydrochloric acid at the temperature specified. Under which of the following conditions would the reaction be slowest? A. Calcium trioxocarbonate ( iv ) chips a 20°C B. CalcIum trioxocarbonate (IV) chips at 40°C C. Calcium trioxocarbonate (IV) powder at 20'C D. Calcium trioxocarbonate (IV) powder at 40'C Detailed Solution- Increasing the surface area of a reactant increases the frequency of collisions and increases the reaction rate.- Chips have a lower surface area compared to powder, so it accounts for the slowest |
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| 8. |
The high solubility of ethanol in water is due to? A. its low boiling point. B. its low freezing point. C. its covalent nature D. hydrogen bonding Detailed SolutionEthanol is an alcohol that is soluble in water. This is because of the hydroxyl group (−OH) in the ethanol that is able to form hydrogen bonds with the water (H2O) molecules. |
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| 9. |
Which of the following pairs of properties of alkali metals decreases down the group? A. First ionization energy and reactivity B. melting point and atomic radius C. Reactivity and electronegativity D. First ionization energy and melting point Detailed Solution- The ionization energy of an atom is the amount of energy that is required to remove an electron from a mole of atoms in the gas phase:- It is possible to remove more electrons from most elements, so this quantity is more precisely known as the first ionization energy, the energy to go from neutral atoms to cations with a 1+ charge. - The ionization energy decreases from top to bottom in groups, and increases from left to right across a period. - The boiling and melting points decrease as you move down the group. |
|
| 10. |
The most suitable process of obtaining water from an aqueous solution of sugar i A. Crystallization B. Distillation C. Filtration D. Decantation Detailed Solution- Crystallization is primarily employed as a separation technique in order to obtain pure crystals of a substance from an impure mixture.- Another important application of crystallization is its use to obtain pure salt from seawater. - Simple syrup crystallizes when enough of the sugar molecules stick to one another that they become insoluble in the water |
| 1. |
Which of the following substances is an example of a fine chemical? A. Sodium hydroxide B. Hydrochloric acid C. Ethylene D. Ammonia Detailed Solution- Fine chemicals are complex, single, pure chemical substances, produced in limited quantities.- Heavy chemicals are produced and handled in large lots and are often in a crude state. - Some examples of heavy chemicals are ammonia, sulfuric acid, and sodium hydroxide. |
|
| 2. |
The IUPAC name of the compound represented by the structure below is ? A. 2- chloro but-I ,3-diene. B. But-1,3-chlorodiene. C. 2-chloro but-diene. D. 3 -chloro but -1.3-diene. |
A |
| 3. |
Which or the following substances is a polypeptide? A. Starch B. Glycogen C. Protein D. Fats Detailed Solution- A polypeptide is defined as a polymer of amino acids joined together by peptide bonds.- Proteins are polymers of amino acids. |
|
| 4. |
Which or the following products could be formed during incomplete combustion of a hydrocarbon.i.Carbon ii. Hydrogen III. Carbon (Il) oxide A. I only B. I and II only C. I and III only D. II and III only Detailed SolutionIncomplete combustion occurs when the supply of air or oxygen is poor. Water is still produced, but carbon monoxide and carbon are produced instead of carbon dioxide. The carbon is released as soot. |
|
| 5. |
What quantity of electrons is lost when one mole of iron (II) ions is oxidized to iron (III) ? A. 0 mole B. 3 moles C. I mole D. 2 moles Detailed SolutionFe\(^2^+\) → Fe\(^3^+\)The pale green Fe2+ is oxidized to orange Fe3+ because it loses an electron. |
| 6. |
What is the mass of silver deposited when 24,125 C of electricity is passed through a solution or silver salt.[Ag = 108, IF = 96,500 C ] A. 432g B. 108g C. 54g D. 27g Detailed SolutionAg + e → Ag1 mole of Ag+ = 108 i.e 108 X 1 X 96500 But, 24,125C will produce ( 108 X 24,125 ) / ( 1 X 96500 ) Ag = 27g |
|
| 7. |
Equal masses of calcium trioxocarbonate(iv) were added to dilute hydrochloric acid at the temperature specified. Under which of the following conditions would the reaction be slowest? A. Calcium trioxocarbonate ( iv ) chips a 20°C B. CalcIum trioxocarbonate (IV) chips at 40°C C. Calcium trioxocarbonate (IV) powder at 20'C D. Calcium trioxocarbonate (IV) powder at 40'C Detailed Solution- Increasing the surface area of a reactant increases the frequency of collisions and increases the reaction rate.- Chips have a lower surface area compared to powder, so it accounts for the slowest |
|
| 8. |
The high solubility of ethanol in water is due to? A. its low boiling point. B. its low freezing point. C. its covalent nature D. hydrogen bonding Detailed SolutionEthanol is an alcohol that is soluble in water. This is because of the hydroxyl group (−OH) in the ethanol that is able to form hydrogen bonds with the water (H2O) molecules. |
|
| 9. |
Which of the following pairs of properties of alkali metals decreases down the group? A. First ionization energy and reactivity B. melting point and atomic radius C. Reactivity and electronegativity D. First ionization energy and melting point Detailed Solution- The ionization energy of an atom is the amount of energy that is required to remove an electron from a mole of atoms in the gas phase:- It is possible to remove more electrons from most elements, so this quantity is more precisely known as the first ionization energy, the energy to go from neutral atoms to cations with a 1+ charge. - The ionization energy decreases from top to bottom in groups, and increases from left to right across a period. - The boiling and melting points decrease as you move down the group. |
|
| 10. |
The most suitable process of obtaining water from an aqueous solution of sugar i A. Crystallization B. Distillation C. Filtration D. Decantation Detailed Solution- Crystallization is primarily employed as a separation technique in order to obtain pure crystals of a substance from an impure mixture.- Another important application of crystallization is its use to obtain pure salt from seawater. - Simple syrup crystallizes when enough of the sugar molecules stick to one another that they become insoluble in the water |