A student tests halogen solution X.
X does not react with potassium chloride solution.
When X is added to potassium iodide solution, iodine is formed.
The student says, "X must be chlorine."
Which response to the student is correct?
The student is correct, because only chlorine can displace iodine from potassium iodide.
The student is wrong, because X could be chlorine or bromine. Both displace iodine from iodide, and neither reacts with chloride.
The student is wrong, because the iodine formed shows that X must be iodine.
The student is wrong, because chlorine would react with potassium chloride, so X must be bromine.
60 exam-style questions on OCR GCSE Chemistry 4.1 Predicting chemical reactions, covering 4.1.1 Properties and trends in Groups 1, 7 and 0, 4.1.2 Properties of the transition metals, 4.1.3 Reactivity predicted from position in the Periodic Table, and 4.1.4 Reactivity of metals and the reactivity series. Each one has a worked solution and a mark scheme showing where the marks go.