Question

two disadvantages of series arrangement for household circuit

Answer 1

if we can series connection
I) if one bulb get diffused then all bulbs get off that is very bad
II) in series connection potential is variable at every circuits so all bulbs does not glow with same ratio

Answer 2

hey your answer is here
1. if one device stops working then all other device in whole circuit stops working .
2 voltage are divided in devices so they don't work properly because they don't get enough voltage