Question

why is a parallel arrangement used in domestic circuit

Answer 1

When appliances are connected in a parallel arrangement, each of them can be put on and off independently. This is a feature that is essential in a house's wiring. Also, if the appliances were wired in series, the potential difference across each appliance would vary depending on the resistance of the appliance.

Answer 2

When appliances are connected in parallel arrangements, then each of them can be put ON and OFF independently. Also If the appliances are weird in series the potential difference across each appliance would vary depending on the resistance of the appliance