Answer:
A gas with a rotten egg smell is evolved
Step-by-step explanation:
When iron fillings and sulphur were heated in the vessel, the following chemical reaction took place;
Fe(s) + S(s) -----> FeS(s)
This is a direct combination reaction.
Subsequently, when dilute H2SO4 is added, the following reaction takes place;
FeS(s) + H2SO4(aq) ------> FeSO4(aq) + H2S(g)
He immediately observes the evolution of a gas with a rotten egg smell.