Core · structured questions. Each generated paper follows the 0620 Paper 3 · Theory format, with the same number and style of questions as the real exam, and comes with a Cambridge-style mark scheme.
A tube is set up with cotton wool soaked in concentrated ammonia at one end and cotton wool soaked in concentrated hydrochloric acid at the other. A white ring of ammonium chloride forms inside the tube, nearer the hydrochloric acid end.
(a)
Name the process by which the gases move along the tube.
[1]
(b)
Explain why the white ring forms nearer the hydrochloric acid end.
[3]
(c)
State one change that would make the white ring form more quickly.
[1]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
diffusion
diffusion B1
1
(b)
ammonia lighter so diffuses faster
ammonia (Mr 17) has a lower relative molecular mass than hydrogen chloride (Mr 36.5) B1 its molecules move faster B1 so ammonia travels further before they meet B1
3
(c)
higher temperature
increase the temperature B1
1
Question 2Structured · 3 marksA* challenge
Copper is used for electrical wiring and saucepan bases.
(a)
Explain why copper has a high melting point.
[2]
(b)
Suggest why copper is a good conductor of thermal energy.
[1]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
strong attraction between ions and electrons
strong electrostatic attraction between the positive ions and the delocalised electrons B1 much energy needed to overcome B1
2
(b)
delocalised electrons carry energy
delocalised electrons move and carry energy through the metal B1
1
Question 3Structured · 14 marks
This question is about metals and alloys.
(a)
Give three physical properties of typical metals.
[3]
(b)
State what is meant by an alloy, and name the metals in bronze.
[2]
(c)
Explain, in terms of the arrangement of particles, why bronze is harder than the pure metals in it.
[3]
(d)
Describe metallic bonding and explain why metals conduct electricity.
[3]
(e)
Magnesium, zinc and copper are added to dilute hydrochloric acid. Describe what is seen with each metal.
[3]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
good conductors; malleable; ductile; high melting point; shiny
Any 3 of: good conductors of heat and electricity; malleable; ductile; high melting / boiling point; shiny B3
3
(b)
mixture of a metal with other elements; copper and tin
a mixture of a metal with other elements (metals or carbon) B1 copper and tin B1
2
(c)
atoms of different sizes; disrupt the regular layers; layers cannot slide easily
the alloy contains atoms of different sizes B1 which disrupt the regular arrangement of layers B1 so the layers cannot slide over each other easily B1
3
(d)
positive ions in sea of delocalised electrons; electrons free to move and carry charge
a lattice of positive ions B1 surrounded by a sea of delocalised electrons B1 the electrons are free to move and carry charge through the metal B1
Calculate the relative molecular masses of hydrogen and carbon dioxide. [Aᵣ: H, 1; N, 14; C, 12; O, 16; Cl, 35.5]
[2]
(c)
Predict which gas diffuses faster, hydrogen or carbon dioxide, at the same temperature. Explain your answer.
[2]
(d)
Explain why diffusion is faster in gases than in liquids.
[2]
(e)
A crystal of potassium manganate(VII) is placed at the bottom of a beaker of water. Describe what is seen over several hours and explain why it is slow.
[3]
(f)
State and explain the effect of increasing temperature on the rate of diffusion.
[2]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
net movement of particles from high to low concentration; due to random movement
net movement of particles from a region of higher concentration to lower concentration B1 as a result of their random movement B1
2
(b)
2; 44
hydrogen: 2 B1 carbon dioxide: 44 B1
2
(c)
hydrogen; lower Mr, molecules move faster
hydrogen B1 it has a lower Mᵣ so its molecules move faster at the same temperature B1
2
(d)
gas particles move faster; more space between them, fewer collisions
gas particles move faster B1 and are further apart so they travel further between collisions B1
2
(e)
purple colour spreads until uniform; slow because liquid particles collide frequently and move slowly
the purple colour spreads out through the water B1 until the colour is the same everywhere B1 slow because particles in a liquid collide often and move slowly B1
3
(f)
faster; particles have more kinetic energy
increases the rate B1 particles have more kinetic energy and move faster B1
2
Question 5Structured · 3 marks
A student wants to find the melting point of a solid.
(a)
Suggest suitable apparatus.
[2]
(b)
State how the melting point shows if the solid is pure.
[1]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
capillary tube, thermometer, water/oil bath
capillary tube with sample B1 thermometer in a heated water/oil bath B1
2
(b)
sharp, fixed melting point
a pure substance melts at a sharp, fixed temperature (impurities lower it/give a range) B1
1
Question 6Structured · 3 marks
Metals are extracted from ores.
(a)
Explain why gold is found uncombined in the Earth’s crust.
Riyaz Shaikh has mentored IGCSE, IB and A Level students for 15+ years, one-on-one, online and in Mumbai. The hardest questions on this site are the ones he uses to find a student's weak points.
Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in