5th ques plz answer

In Room P, bulbs are connected in series. If one bulb get fused, the circuit connecting Live and neutral points are disconnected to other bulbs.

Hence there is no current flow and other bulbs will not glow

 

In Room Q, bulbs are connected in parallel to Live and neutral points. If one bulb is getting fused, other bulbs are still connected to Live and neutral points. Hence the current flow to other bulbs are not affected and other bulbs will glow.