GCSE Combined Science Foundation Short Paper B
Covers Quantitative Chemistry, Chemical Changes, Energy and 3 more.
Questions
Question 1 [2 marks]
Particle Model of Matter
A block of wood has a mass of 60 g and a volume of 75 cm^3.
Calculate the density of the wood. Use density = mass / volume.
Question 2 [2 marks]
Quantitative Chemistry
Magnesium oxide has the formula MgO.
Calculate the relative formula mass (Mr) of magnesium oxide. Relative atomic masses: Mg = 24, O = 16.
Question 3 [2 marks]
Energy
Energy can be transferred between different energy stores.
State the energy store that increases when a ball is thrown upwards.
State the energy store that increases when a car accelerates.
Question 4 [2 marks]
Chemical Changes
Acids react with reactive metals, such as magnesium and zinc.
State the two products formed in the general reaction between an acid and a reactive metal.
Question 5 [3 marks]
Energy
A car of mass 1200 kg travels at a speed of 15 m/s.
Calculate the kinetic energy of the car. Use KE = 1/2 m v^2.
Question 6 [3 marks]
Electricity
A UK three-pin plug contains a live wire, a neutral wire and an earth wire, each covered in insulation of a different colour.
State the colour of the insulation on each of the live, neutral and earth wires.
Question 7 [3 marks]
Energy
Energy is conserved in any change involving energy transfer.
State what is meant by the conservation of energy, and describe what eventually happens to energy that is dissipated (wasted).
Question 8 [3 marks]
Forces
A cyclist travels 450 m in 30 s.
Calculate the average speed of the cyclist. Use speed = distance / time.
Question 9 [5 marks]
Energy
A weightlifter raises a 120 kg barbell through a height of 2.0 m in 1.5 s.
Calculate the work done raising the barbell, and calculate the power developed by the weightlifter.
Question 10 [5 marks]
Electricity
Two resistors, of resistance 15 ohms and 25 ohms, are connected in series with a 20 V supply.
Calculate the current flowing in the circuit, and calculate the potential difference across the 15 ohm resistor.
Question 11 [5 marks]
Energy
A spring has a spring constant of 40 N/m.
The spring is stretched by 0.15 m from its natural length.
Calculate the elastic potential energy stored in the spring. Use elastic potential energy = 0.5 k e^2.
Question 12 [5 marks]
Quantitative Chemistry
A 12.0 g sample of magnesium carbonate is completely decomposed by heating, producing magnesium oxide and carbon dioxide gas.
6.6 g of carbon dioxide gas is given off.
Calculate the mass of magnesium oxide remaining, using conservation of mass, and calculate the percentage of the original mass that was lost as carbon dioxide gas.
Model solutions
| Question 1[2 marks] | |
|---|---|
| Answer or working | Marks |
| substituting 60 / 75 | M1 |
| 0.8 g/cm^3 | A1 |
| Question 2[2 marks] | |
|---|---|
| Answer or working | Marks |
| adding the relative atomic masses of Mg and O | M1 |
| 40 | A1 |
| Question 3[2 marks] | |
|---|---|
| Answer or working | Marks |
| the gravitational potential energy store increasing | B1 |
| the kinetic energy store increasing | B1 |
| Final answer: GPE store increases; KE store increases | |
| Question 4[2 marks] | |
|---|---|
| Answer or working | Marks |
| salt as a product | B1 |
| hydrogen gas as a product | B1 |
| Final answer: salt + hydrogen | |
| Question 5[3 marks] | |
|---|---|
| Answer or working | Marks |
| substituting into KE = 1/2 m v^2 | M1 |
| 15^2 = 225 | M1 |
| 135000 J (135 kJ) | A1 |
| Question 6[3 marks] | |
|---|---|
| Answer or working | Marks |
| the live wire being brown | B1 |
| the neutral wire being blue | B1 |
| the earth wire being green and yellow | B1 |
| Final answer: Live: brown; neutral: blue; earth: green and yellow | |
| Question 7[3 marks] | |
|---|---|
| Answer or working | Marks |
| stating energy cannot be created or destroyed | B1 |
| stating energy can only be transferred, stored or dissipated, from one store to another | B1 |
| stating dissipated energy spreads out to the surroundings, becoming increasingly difficult to use for further useful work | B1 |
| Final answer: Energy cannot be created or destroyed, only transferred between stores; dissipated energy spreads out and becomes harder to use usefully | |
| Question 8[3 marks] | |
|---|---|
| Answer or working | Marks |
| substituting 450 / 30 | M1 |
| 15 | A1 |
| the unit m/s | B1 |
| Final answer: 15 m/s | |
| Question 9[5 marks] | |
|---|---|
| Answer or working | Marks |
| using work done = GPE = m g h | M1 |
| substituting 120 x 9.8 x 2.0 | M1 |
| 2352 J | A1 |
| power = work done / time, 2352 / 1.5 | M1 |
| 1568 W | A1 |
| Final answer: 2352 J of work done; 1568 W of power | |
| Question 10[5 marks] | |
|---|---|
| Answer or working | Marks |
| total resistance = 15 + 25 = 40 ohms | M1 |
| using I = V / R, substituting 20 / 40 | M1 |
| 0.5 A | A1 |
| using V = I R for the 15 ohm resistor, substituting 0.5 x 15 | M1 |
| 7.5 V | A1 |
| Final answer: 0.5 A current; 7.5 V across the 15 ohm resistor | |
| Question 11[5 marks] | |
|---|---|
| Answer or working | Marks |
| using elastic potential energy = 0.5 k e^2 | M1 |
| substituting 0.15^2 = 0.0225 | M1 |
| 0.5 x 40 x 0.0225 | M1 |
| 0.45 J | A1 |
| stating this calculation only applies while the spring is not stretched beyond its limit of proportionality | B1 |
| Question 12[5 marks] | |
|---|---|
| Answer or working | Marks |
| using conservation of mass: total mass of reactants = total mass of products | M1 |
| mass of magnesium oxide = 12.0 - 6.6 | M1 |
| 5.4 g | A1 |
| percentage = (6.6 / 12.0) x 100 | M1 |
| 55% | A1 |
| Final answer: 5.4 g of magnesium oxide remains; 55% of the original mass was lost as carbon dioxide gas | |