The questions are on the density test. Take it under real conditions before reading the mark scheme.
Quick answer: Density is the mass of a material per unit of volume, found with the formula density = mass ÷ volume. This mark scheme gives the model answers and the marks for the 8 questions of the grade 6 science test on density, from define density to salt and the egg, with the equivalent answers to accept.
Award marks as shown, and accept equivalent correct methods. For explanations, give a mark for each correct scientific idea; do not penalise spelling if the meaning is clear.
Level: Grade 6 science (Year 7 · Class 6) · Curriculum: MS-PS1-2
Question 1 Define density (2 marks)
Density is the mass per unit volume of a material. ρ = m ÷ V, where ρ is density, m is mass and V is volume.Marking: 1 mark for the definition, 1 mark for the formula with symbols explained.
Question 2 Unknown metal block (3 marks)
- 10.0 × 3.0 × 2.0 = 60 cm³.
- 162 ÷ 60 = 2.7 g/cm³.
- Aluminium.
Marking: 1 mark each.
Question 3 Mass of sea water (2 marks)
m = ρ × V = 1.03 × 400 = 412 g.Marking: 1 mark for the correct formula and substitution, 1 mark for the answer with unit.
Question 4 Bar chart (3 marks)
- Pine and ice.
- 11.3 g/cm³.
- 11.3 ÷ 2.7 = 4.2 times.
Marking: 1 mark each.
Question 5 Steel ship (3 marks)
The hull is hollow and holds a large volume of air. The ship’s mass is spread over a large volume, so its average density is below that of water, and it floats.Marking: 1 mark for the hollow shape or air, 1 mark for average density, 1 mark for comparing with water.
Question 6 Sealed metal box (3 marks)
- 480 ÷ 600 = 0.80 g/cm³.
- 0.80 is less than 1.00, so it floats.
- 0.80 ÷ 1.00 = 80 %.
Marking: 1 mark each.
Question 7 Density units (2 marks)
- 13.6 × 1000 = 13 600 kg/m³.
- 1.2 ÷ 1000 = 0.0012 g/cm³.
Marking: 1 mark each.
Question 8 Salt and the egg (2 marks)
Dissolving salt increases the density of the water. When the water becomes denser than the egg, the egg floats.Marking: 1 mark for the density of the liquid rising, 1 mark for comparing it with the egg.
