In a laboratory demonstration, small, equal-sized pieces of lithium, sodium, and potassium are added to separate troughs of water. Only potassium reacts vigorously enough to immediately ignite with a lilac flame. Potassium produces a flame because it:
is the most reactive of the three metals
has the highest melting point of the three metals
is the densest metal of the three
is the only one of the three metals that reacts with water
Practise Edexcel GCSE Chemistry Group 1 with exam-style questions for Foundation and Higher tier. 51 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.
