When looking at the equilibrium between silver bromide and its aqueous ions, what could be added to solution to promote precipitation of silver bromide?

NaBr

Explanation:

When AgBr is dissolved in water, the following equilibrium is set up in solution;

AgBr(s)⇄Ag^+(aq) + Br^- (aq)

If we dissolve NaBr in the water, a common ion (Br^-) is now introduced into the system. This increases the concentration of Br^- and favours the reverse reaction hence more AgBr is precipitated. This is known as common ion effect.

the correct answer would be b) volume versus temperature, because they are also directly proportional.