(i) Parallel connection is a better way to connect lights and other appliances in domestic circuit.
It is because
(a) When we connect a number of devices in parallel combination, each device gets the same potential as provided by the battery and it keeps on working even if other devices stop working.
(b) Parallel connection is helpful when each device has different resistances and requires different current for its operation as in this case the current divides itself through different devices
unlike series connection.
(ii) Electrician has made series connection of all the lamps in electric circuit of house because of which if one lamp gets fused, all the other lamps stop working.
This is due to the fact that when devices are connected in series then if one device fails, the circuit gets broken and all the devices in that circuit stop working.