A faulty heater produces carbon monoxide. The gas cannot be reliably detected by sight or smell. A student suggests using visible soot as the only warning of danger.
Evaluate this suggestion and explain the health risk of carbon monoxide.
[4 marks]AQA GCSE Combined Science November 2021 Chemistry Paper 2H
5 questions on this paper's topics
21:001 of 5
Sewage enters a treatment works containing rags, grit, suspended organic solids and dissolved organic material. A student proposes only filtration followed by chlorination.
Explain a more complete sewage-treatment sequence and the roles of microorganisms.
[4 marks]A town collects 12 tonnes of glass. Sorting removes 8% as contamination. All remaining glass can replace virgin glass material in this simplified model.
.1
Calculate the mass available to replace virgin material.
[2 marks].2
Explain why reducing packaging use can give benefits beyond recycling the same mass.
[2 marks]A refinery has 60 tonnes of a long-chain fraction but buyers want only 20 tonnes. Catalytic cracking converts 75% of the 40-tonne surplus into shorter fuel molecules; the rest becomes other useful products.
.1
Calculate the mass of shorter fuel molecules obtained from the surplus.
[2 marks].2
Explain why cracking is useful and state one chemical test that distinguishes an alkene product from an alkane.
[2 marks]A solid decomposes reversibly into two gases. In experiment A it is heated in an open tube; in experiment B it is heated in a sealed vessel. In this model, gases escape from A but remain in B.
Explain why B can establish dynamic equilibrium but A cannot establish that equilibrium while gas escapes.
[4 marks]