Which statement about an atom is correct?
It normally has equal numbers of protons and electrons
Its nucleus contains all of its protons, neutrons and electrons
Its electrons each have a relative mass of 1, like protons
Most of its mass is found in the electron shells around it
46 exam-style questions on Edexcel GCSE Chemistry 2.1 Atomic structure, covering 2.1.1 Development of the atomic model, 2.1.2 Structure of the atom and subatomic particles, 2.1.3 Mass number, isotopes and relative atomic mass, and 2.1.4 Calculating relative atomic mass from isotopic abundance. Each one has a worked solution and a mark scheme showing where the marks go.