An element has three isotopes, with mass numbers 36, 38 and 40. Each atom of the isotope with mass number 38 contains 20 neutrons. The relative atomic mass of the element is 39.9.
Which statement must be correct?
The atomic number of the element is 20
The most abundant isotope has 20 neutrons in each atom
Each atom of the element has a relative mass of 39.9
The most abundant isotope has 22 neutrons in each atom
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.