(a(i))[1]
State the symbol of the element that is a monoatomic gas at room temperature.
(a(ii))[1]
State the symbol of the element that is liquid at room temperature.
(a(iii))[1]
State the symbol of the element that forms a stable ion of type X$^{2-}$.
(a(iv))[1]
State the symbol of the element that is extracted from hematite.
(a(v))[1]
State the symbol of the element that forms an ion whose aqueous solution gives a grey-green precipitate on addition of aqueous ammonia.
(b(i))[2]
State the meaning of the term isotopes.
(b(ii))[2]
Deduce the number of protons and neutrons in this isotope.
(c)[1]
Complete the electronic structure of a magnesium atom.