(a)[2]
Draw a dot-and-cross diagram to represent the electronic structure in an ethyne molecule. Show only the outer-shell electrons of each atom.
(b(i))[2]
A 0.130 g sample of ethyne gas is given. Calculate how many ethyne molecules are present in this sample. One mole of ethyne contains $6.02 \times 10^{23}$ molecules.
(b(ii))[1]
Calculate the overall number of atoms in this ethyne sample.
(c)[1]
Explain why ethyne counts as a hydrocarbon.
(d)[2]
Suggest what you would observe when ethyne gas is bubbled through aqueous bromine.
(e)[1]
Ethyne is produced when calcium carbide reacts with water. Calcium carbide contains only the ions $\mathrm{Ca^{2+}}$ and $\mathrm{C_2^{2-}}$. Deduce the formula of calcium carbide.