A helium atom has two electrons. A magnesium atom also has two electrons in its outer shell.
Which statement best explains why helium is placed in Group 0 and not in Group 2?
Helium atoms lose their two electrons more easily than magnesium, as they are nearer the nucleus
Helium atoms join in pairs to form He2\mathrm{He_{2}}He2 molecules, so each atom shares electrons to fill its shell
Helium has a lower relative atomic mass than magnesium, so it must be placed at the top of the table
Helium's only shell is full, so like the other noble gases it does not readily lose, gain or share electrons
44 exam-style questions on Edexcel GCSE Chemistry 7.3 Group 0, covering 7.3.1 The noble gases. Each one has a worked solution and a mark scheme showing where the marks go.