When calcium carbonate is added to dilute hydrochloric acid, carbon dioxide gas is produced. Which observation shows that a gas is produced?
a bright blue precipitate forms
effervescence is observed
the solid completely dissolves
the acid turns a green colour
Practise Edexcel GCSE Chemistry Acids with exam-style questions for Foundation and Higher tier. 100 questions, matched to the Edexcel GCSE Chemistry (1CH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.