(a(i))[1]
Which element acts as a catalyst in the Haber process?
(a(ii))[1]
Which element accounts for 21% of dry air?
(a(iii))[1]
Which element may be formed when hydrocarbons are cracked?
(a(iv))[1]
Which element forms aqueous ions with a $3+$ charge that produce a white precipitate when aqueous ammonia is added?
(a(v))[1]
Which element has an atom with just three electrons in its outer shell?
(b)[4]
Complete the table to give the number of electrons and neutrons in the potassium atom $^{41}_{19}\text{K}$ and in the oxide ion $^{17}_{8}\text{O}^{2-}$.