State and explain how the oxidation numbers change in the chlorides of the elements Na, Mg, Al and Si.
Describe how phosphorus(V) chloride reacts with water, and write an equation for the reaction.
If microwave radiation is passed through phosphorus(III) chloride, $\text{PCl}_3$, at low pressure, a different phosphorus chloride, $B$, is produced. $B$ is made up of $69.6\%$ chlorine by mass and $30.4\%$ phosphorus by mass, and it has $M_r \approx 200$.
Calculate the empirical and molecular formulae of $B$.
Assuming phosphorus and chlorine have their usual valencies, draw the displayed formula of $B$, showing every bond and lone pair.
Calculate the oxidation number of phosphorus present in $B$.
One mole of $B$ reacts with four moles of water. Suggest the structure of the phosphorus-containing product formed in this reaction.