WASSCE Science Practice: Test your ability to solve calculation-based questions in Chemistry and Physics. Choose the correct answer from options A–D. Try all the questions before checking the answer key at the bottom.
Instruction: Choose the correct answer for each question. Where necessary, use \(g = 10\,m\,s^{-2}\), \(N_A = 6.02\times10^{23}\,mol^{-1}\), and \(R = 8.31\,J\,mol^{-1}K^{-1}\).
PART A: CHEMISTRY — CALCULATION QUESTIONS
1. Relative Molecular Mass
What is the relative molecular mass of \(H_2SO_4\)?
A. 96 B. 98 C. 100 D. 102
2. Mole Calculation
How many moles are present in 18 g of water, \(H_2O\)?
A. 0.5 mol B. 1.0 mol C. 1.5 mol D. 2.0 mol
3. Number of Particles
How many molecules are present in 2 mol of carbon dioxide?
A. \(1.20\times10^{23}\) B. \(3.01\times10^{23}\) C. \(1.204\times10^{24}\) D. \(6.02\times10^{24}\)
4. Mass from Moles
What mass of sodium hydroxide, \(NaOH\), is present in 0.50 mol?
A. 10 g B. 20 g C. 30 g D. 40 g
5. Percentage Composition
What is the percentage by mass of oxygen in \(CO_2\)?
A. 27.3% B. 50.0% C. 72.7% D. 80.0%
6. Empirical Formula
A compound contains 40% carbon, 6.7% hydrogen and 53.3% oxygen. What is its empirical formula?
A. \(CH_2O\) B. \(C_2H_4O\) C. \(CH_4O\) D. \(C_2H_2O\)
7. Concentration
5.85 g of NaCl is dissolved to make 500 cm³ of solution. What is the concentration in mol dm⁻³? [NaCl = 58.5]
A. 0.10 mol dm⁻³ B. 0.20 mol dm⁻³ C. 0.50 mol dm⁻³ D. 1.00 mol dm⁻³
8. Moles in a Solution
How many moles of solute are present in 250 cm³ of a 0.40 mol dm⁻³ solution?
A. 0.05 mol B. 0.10 mol C. 0.20 mol D. 0.40 mol
9. Dilution
What volume of 2.0 mol dm⁻³ HCl is required to prepare 500 cm³ of 0.50 mol dm⁻³ HCl?
A. 100 cm³ B. 125 cm³ C. 150 cm³ D. 250 cm³
10. Titration
25.0 cm³ of 0.10 mol dm⁻³ NaOH completely neutralizes 20.0 cm³ of HCl. What is the concentration of the HCl?
A. 0.080 mol dm⁻³ B. 0.100 mol dm⁻³ C. 0.125 mol dm⁻³ D. 0.150 mol dm⁻³
11. Gas Volume
What volume will 0.50 mol of a gas occupy at room temperature and pressure if 1 mol occupies 24 dm³?
A. 6 dm³ B. 12 dm³ C. 18 dm³ D. 24 dm³
12. Gas Moles
What amount of gas is contained in 48 dm³ at room temperature and pressure, assuming 1 mol occupies 24 dm³?
A. 0.5 mol B. 1 mol C. 2 mol D. 4 mol
13. Stoichiometry
For the reaction \(2H_2 + O_2 \rightarrow 2H_2O\), how many moles of water are produced from 3 mol of hydrogen, assuming oxygen is in excess?
A. 1 mol B. 2 mol C. 3 mol D. 6 mol
14. Thermal Energy
How much heat is required to raise the temperature of 100 g of water from 20°C to 30°C? Take the specific heat capacity of water as \(4.2\,Jg^{-1}°C^{-1}\).
A. 420 J B. 840 J C. 4,200 J D. 42,000 J
15. Enthalpy
A reaction releases 50 kJ of energy when 2 mol of a substance reacts. What is the enthalpy change per mole?
A. +25 kJ mol⁻¹ B. -25 kJ mol⁻¹ C. +100 kJ mol⁻¹ D. -100 kJ mol⁻¹
16. pH
What is the pH of a solution whose hydrogen ion concentration is \(1.0\times10^{-3}\) mol dm⁻³?
A. 2 B. 3 C. 4 D. 11
17. Hydrogen Ion Concentration
What is the hydrogen ion concentration of a solution with pH 2?
A. \(1\times10^{-2}\) mol dm⁻³ B. \(2\times10^{-2}\) mol dm⁻³ C. \(1\times10^{-7}\) mol dm⁻³ D. \(1\times10^{-12}\) mol dm⁻³
18. Percentage Yield
A reaction has a theoretical yield of 20 g but produces 15 g experimentally. What is the percentage yield?
A. 50% B. 60% C. 75% D. 80%
19. Percentage Purity
A 10 g sample contains 8 g of pure calcium carbonate. What is its percentage purity?
A. 20% B. 50% C. 80% D. 90%
20. Electrolysis
A current of 2 A flows through an electrolytic cell for 30 minutes. What quantity of electricity passes through the cell?
A. 30 C B. 60 C C. 1,800 C D. 3,600 C
21. Molar Mass
A substance has 0.25 mol and a mass of 15 g. What is its molar mass?
A. 30 g mol⁻¹ B. 45 g mol⁻¹ C. 60 g mol⁻¹ D. 75 g mol⁻¹
22. Atomic Mass
Element X has two isotopes: 60% of X-10 and 40% of X-11. What is its relative atomic mass?
A. 10.2 B. 10.4 C. 10.6 D. 10.8
23. Rate of Reaction
The concentration of a reactant falls from 0.80 mol dm⁻³ to 0.20 mol dm⁻³ in 30 seconds. What is the average rate of disappearance?
A. 0.01 mol dm⁻³ s⁻¹ B. 0.02 mol dm⁻³ s⁻¹ C. 0.03 mol dm⁻³ s⁻¹ D. 0.06 mol dm⁻³ s⁻¹
24. Boyle's Law
A gas occupies 600 cm³ at a pressure of 100 kPa. What volume will it occupy at 150 kPa, assuming temperature remains constant?
A. 300 cm³ B. 400 cm³ C. 600 cm³ D. 900 cm³
25. Charles' Law
A gas occupies 200 cm³ at 300 K. What volume will it occupy at 450 K at constant pressure?
A. 250 cm³ B. 300 cm³ C. 350 cm³ D. 400 cm³
PART B: PHYSICS — CALCULATION QUESTIONS
26. Speed
A car travels 150 m in 10 s. What is its average speed?
A. 10 m/s B. 15 m/s C. 20 m/s D. 25 m/s
27. Acceleration
A car increases its velocity from 10 m/s to 30 m/s in 5 s. What is its acceleration?
A. 2 m/s² B. 4 m/s² C. 6 m/s² D. 8 m/s²
28. Distance
An object moves at a constant speed of 12 m/s for 20 s. How far does it travel?
A. 120 m B. 180 m C. 240 m D. 360 m
29. Force
A force of 50 N acts on a mass of 10 kg. What acceleration is produced?
A. 2 m/s² B. 5 m/s² C. 10 m/s² D. 20 m/s²
30. Weight
What is the weight of a 60 kg person on Earth? Take \(g=10\,m/s^2\).
A. 60 N B. 100 N C. 600 N D. 6,000 N
31. Momentum
A 5 kg object moves at 4 m/s. What is its momentum?
A. 1.25 kg m/s B. 9 kg m/s C. 20 kg m/s D. 25 kg m/s
32. Kinetic Energy
What is the kinetic energy of a 2 kg object moving at 10 m/s?
A. 20 J B. 50 J C. 100 J D. 200 J
33. Potential Energy
A 5 kg object is raised through a height of 4 m. What gravitational potential energy does it gain?
A. 20 J B. 50 J C. 100 J D. 200 J
34. Work Done
A force of 40 N moves an object through 5 m in the direction of the force. What work is done?
A. 8 J B. 45 J C. 200 J D. 400 J
35. Power
A machine does 6,000 J of work in 20 seconds. What is its power?
A. 100 W B. 200 W C. 300 W D. 600 W
36. Pressure
A force of 200 N acts on an area of 0.5 m². What pressure is produced?
A. 100 Pa B. 200 Pa C. 400 Pa D. 800 Pa
37. Density
A substance has a mass of 500 g and a volume of 100 cm³. What is its density?
A. 0.2 g/cm³ B. 2 g/cm³ C. 5 g/cm³ D. 50 g/cm³
38. Moment of a Force
A force of 20 N acts perpendicular to a lever at a distance of 0.5 m from the pivot. What is the moment?
A. 5 Nm B. 10 Nm C. 20 Nm D. 40 Nm
39. Simple Machines
A machine has a mechanical advantage of 5 and an effort of 20 N. What load can it lift?
A. 4 N B. 25 N C. 100 N D. 200 N
40. Efficiency
A machine receives 500 J of energy and produces 400 J of useful output energy. What is its efficiency?
A. 40% B. 60% C. 80% D. 90%
41. Ohm's Law
A current of 2 A flows through a resistor of 6 Ω. What is the potential difference across the resistor?
A. 3 V B. 8 V C. 12 V D. 18 V
42. Electrical Power
An electrical appliance operates at 240 V and draws a current of 5 A. What is its power?
A. 48 W B. 120 W C. 1,200 W D. 2,400 W
43. Electrical Energy
A 1,000 W appliance is used for 2 hours. How much electrical energy does it consume in kWh?
A. 0.5 kWh B. 1 kWh C. 2 kWh D. 4 kWh
44. Resistance
A potential difference of 12 V produces a current of 3 A through a conductor. What is its resistance?
A. 2 Ω B. 4 Ω C. 9 Ω D. 36 Ω
45. Wave Speed
A wave has a frequency of 50 Hz and a wavelength of 4 m. What is its speed?
A. 12.5 m/s B. 54 m/s C. 100 m/s D. 200 m/s
46. Frequency
A wave has a period of 0.02 s. What is its frequency?
A. 20 Hz B. 40 Hz C. 50 Hz D. 100 Hz
47. Lens Power
A converging lens has a focal length of 0.25 m. What is its power?
A. 0.25 D B. 2 D C. 4 D D. 25 D
48. Heat Energy
How much energy is needed to heat 2 kg of water through 5°C? Take the specific heat capacity of water as \(4,200\,Jkg^{-1}K^{-1}\).
A. 4,200 J B. 8,400 J C. 21,000 J D. 42,000 J
49. Frequency of Rotation
A wheel makes 120 complete revolutions in 60 seconds. What is its frequency?
A. 0.5 Hz B. 1 Hz C. 2 Hz D. 4 Hz
50. Radioactive Decay
A radioactive substance has a half-life of 5 years. If its initial mass is 80 g, what mass remains after 15 years?
A. 5 g B. 10 g C. 20 g D. 40 g
ANSWER KEY
Check your answers only after attempting all 50 questions.
| Question | Answer | Question | Answer | Question | Answer | Question | Answer | Question | Answer |
|---|---|---|---|---|---|---|---|---|---|
| 1 | B | 11 | B | 21 | C | 31 | C | 41 | C |
| 2 | B | 12 | C | 22 | B | 32 | C | 42 | C |
| 3 | C | 13 | C | 23 | B | 33 | D | 43 | C |
| 4 | B | 14 | C | 24 | B | 34 | C | 44 | B |
| 5 | C | 15 | B | 25 | B | 35 | C | 45 | D |
| 6 | A | 16 | B | 26 | B | 36 | C | 46 | C |
| 7 | B | 17 | A | 27 | B | 37 | C | 47 | C |
| 8 | B | 18 | C | 28 | C | 38 | B | 48 | D |
| 9 | B | 19 | C | 29 | B | 39 | C | 49 | C |
| 10 | C | 20 | C | 30 | C | 40 | C | 50 | B |
How to Use These Questions
These questions are useful for SHS students preparing for Chemistry and Physics examinations, especially students who want to improve their ability to apply formulas rather than simply memorize definitions.
Tip: Write down the formula first, substitute the given values, carry out the calculation, and then compare your result with the available options.
Recommended practice: Try to complete all 50 questions within 60 minutes without checking the answer key.
SOURCE:
