Which gas increased in concentration in the Earth's atmosphere as a direct result of photosynthesis by early organisms?
A
Carbon dioxide
B
Nitrogen
C
Oxygen
D
Water vapour
Markscheme
Interpreting and interacting with earth systems Questions
32 exam-style questions on OCR GCSE Chemistry Interpreting and interacting with earth systems. Each one has a worked solution and a mark scheme showing where the marks go.