(a) An atom consists of electrons surrounding a nucleus made up of protons and neutrons. State which of these particles

1. (a)(i)have an equal and opposite charge,[1]
2. (a)(ii)have almost equal mass.[1]
3. (b)(i)The nuclide notation for carbon-14 is ¹⁴₆C. Carbon-14 decays by beta emission to a stable isotope of nitrogen (N). Write numbers in the empty boxes below to show the nuclide notation for this isotope of nitrogen. ¹⁴₆C → □□N + β[2]
4. (b)(ii)The half-life of carbon-14 is 5700 years. A sample of wood from a living tree contains 2.4 × 10¹² atoms of carbon-14. A similar sample of the same size is taken from an old piece of wood. It contains 6.0 x 10¹¹ atoms of carbon-14. Calculate the age of the old piece of wood.[2]