(a(i))[1]
Which element makes up 21% of air?
(a(ii))[1]
Which element reacts with water to make a solution that changes red litmus paper to blue?
(a(iii))[1]
Which element forms ions of type $X^{3+}$ that give a green precipitate when tested with aqueous sodium hydroxide?
(a(iv))[1]
Which element is a red-brown liquid at room temperature and pressure?
(a(v))[1]
Which element is a noble gas with just three complete electron shells?
(b)[3]
Which of these metals would be best for the frame of an aircraft? Explain your answer by using information from the table.