The table below shows the number of protons, neutrons, electrons and the mass numbers of some atoms Q, R, Y and Z. The letters used are not the usual symbols of the elements. Complete the table above. i. Identify a pair of isotopes from the atoms represented by letters Q, R, Y and Z. ii. If the two isotopes occur in nature in equal proportions, calculate the relative atomic mass. iii. Draw a dot and cross diagram for the bonding in the compound formed between Z and oxygen. Write an equation for the reaction. Z reacts with oxygen to form a compound. Write an equation for the reaction.