Year :
2002
Title :
Chemistry
Exam :
WASSCE/WAEC MAY/JUNE
Paper 1 | Objectives
21 - 30 of 52 Questions
| # | Question | Ans |
|---|---|---|
| 21. |
What volume of hydrogen will be produced if 100cm3 of ammonia is completely decomposed at constant temperature and pressure? The equation for reaction is 2NH3(g) → N2(g) + 3H2(g) A. 50cm3 B. 150cm3 C. 200cm3 D. 300cm3 Detailed SolutionAccording to the equation 2NH3 → N3 + 3H22 x 22400cm3 of ammonia will produce 3 x 22400cm3 of hydrogen If 100cm3 of NH3 is used. :. H2 volume = \(\frac{100}{2x22400} x 3x22400 =150cm3 |
|
| 22. |
Calculate the mass of chlorine gas which occupies a volume of 1.12 dm\(^3\) a volume of 1.12 dm\(^3\) at s.t.p [Cl = 35.5, 1 mole og gas occupies 22.4 dm\(^3\) at s. t. p ] A. 1.80g B. 3.55g C. 7.10g D. 15.50g Detailed Solution1 mole Cl\(_2\) occupy 22.4dm\(^3\)i.e 2 x 35.5 → 22.4 ; x → 1. 12 :. x = \(\frac{1.12}{22.4}\) x 2 x 35.5 = 3.55 |
|
| 23. |
Determine the mass of sulphur (IV) oxide obtained when 91.0g of oxygen reacts completely with sulphur according to the following equation: S(s) + O2(g) → SO2(g) [S = 32; O = 16] A. 123g B. 139g C. 155g D. 182g Detailed SolutionS + O2 → SO2. According to the equation 32g of O2 produced 64g of SO2therefor 91g of O2 will produce yg of SO2 y = \(\frac{91}{32}\) |
|
| 24. |
The gas given off when NH4 Cl is heated with an alkali is A. H2 B. Cl2 C. N2 D. NH3 |
D |
| 25. |
A major factor considered in selecting a suitable method for preparing a simple salt is its A. crystalline form B. melting point C. reactivity with dilute acids D. solubility in water |
D |
| 26. |
Which of following acids forms normal salts only? A. Tetraoxosulphate (VI) acid B. Trioxosulphate (IV) acid C. Acetic acid D. Tetraoxophosphate (V) acid Detailed SolutionSo we can determine that the basicity of Acetic acid is 1 because it releases one hydrogen ion in an aqueous solution.Due to this they act as very weak acids. When weak acid reacts with strong base, they tend to form normal salt. |
|
| 27. |
A substance is said to be hygroscopic if it absorbs A. water from the atmosphere to form a solution B. heat from the surrounding C. carbon (IV) oxide from the atmosphere D. moisture from the atmosphere without dissolving |
D |
| 28. |
Which of the following substances increases in mass when heated in air? A. Sodium chloride B. lodine crystals C. Magnesium ribbon D. Copper (ll) oxide |
C |
| 29. |
Calculate the mass of sodium hydroxide in 5.00 dm3 of a 0.125 mol dm-3 solution. [NaOH = 40 g mol-1] A. 0.0156 g B. 0.625 g C. 1.00 g D. 25.0 g Detailed Solution1 mole of NaOH per dm3 has a mass of 40g.mass of NaOH in 0.125mole = 0.125 x 40 = 5g. mass in 5.00 dm3 of the solution. = 5 x 5 = 25.0g. |
|
| 30. |
Which of the following salt solutions will have a pH greater than 7? A. NaCI(aq) B. Na2CO3(aq) C. Na2SO4(aq) D. NaHSO4(aq) |
B |
| 21. |
What volume of hydrogen will be produced if 100cm3 of ammonia is completely decomposed at constant temperature and pressure? The equation for reaction is 2NH3(g) → N2(g) + 3H2(g) A. 50cm3 B. 150cm3 C. 200cm3 D. 300cm3 Detailed SolutionAccording to the equation 2NH3 → N3 + 3H22 x 22400cm3 of ammonia will produce 3 x 22400cm3 of hydrogen If 100cm3 of NH3 is used. :. H2 volume = \(\frac{100}{2x22400} x 3x22400 =150cm3 |
|
| 22. |
Calculate the mass of chlorine gas which occupies a volume of 1.12 dm\(^3\) a volume of 1.12 dm\(^3\) at s.t.p [Cl = 35.5, 1 mole og gas occupies 22.4 dm\(^3\) at s. t. p ] A. 1.80g B. 3.55g C. 7.10g D. 15.50g Detailed Solution1 mole Cl\(_2\) occupy 22.4dm\(^3\)i.e 2 x 35.5 → 22.4 ; x → 1. 12 :. x = \(\frac{1.12}{22.4}\) x 2 x 35.5 = 3.55 |
|
| 23. |
Determine the mass of sulphur (IV) oxide obtained when 91.0g of oxygen reacts completely with sulphur according to the following equation: S(s) + O2(g) → SO2(g) [S = 32; O = 16] A. 123g B. 139g C. 155g D. 182g Detailed SolutionS + O2 → SO2. According to the equation 32g of O2 produced 64g of SO2therefor 91g of O2 will produce yg of SO2 y = \(\frac{91}{32}\) |
|
| 24. |
The gas given off when NH4 Cl is heated with an alkali is A. H2 B. Cl2 C. N2 D. NH3 |
D |
| 25. |
A major factor considered in selecting a suitable method for preparing a simple salt is its A. crystalline form B. melting point C. reactivity with dilute acids D. solubility in water |
D |
| 26. |
Which of following acids forms normal salts only? A. Tetraoxosulphate (VI) acid B. Trioxosulphate (IV) acid C. Acetic acid D. Tetraoxophosphate (V) acid Detailed SolutionSo we can determine that the basicity of Acetic acid is 1 because it releases one hydrogen ion in an aqueous solution.Due to this they act as very weak acids. When weak acid reacts with strong base, they tend to form normal salt. |
|
| 27. |
A substance is said to be hygroscopic if it absorbs A. water from the atmosphere to form a solution B. heat from the surrounding C. carbon (IV) oxide from the atmosphere D. moisture from the atmosphere without dissolving |
D |
| 28. |
Which of the following substances increases in mass when heated in air? A. Sodium chloride B. lodine crystals C. Magnesium ribbon D. Copper (ll) oxide |
C |
| 29. |
Calculate the mass of sodium hydroxide in 5.00 dm3 of a 0.125 mol dm-3 solution. [NaOH = 40 g mol-1] A. 0.0156 g B. 0.625 g C. 1.00 g D. 25.0 g Detailed Solution1 mole of NaOH per dm3 has a mass of 40g.mass of NaOH in 0.125mole = 0.125 x 40 = 5g. mass in 5.00 dm3 of the solution. = 5 x 5 = 25.0g. |
|
| 30. |
Which of the following salt solutions will have a pH greater than 7? A. NaCI(aq) B. Na2CO3(aq) C. Na2SO4(aq) D. NaHSO4(aq) |
B |