Question

uses 3 of bleaching powder

Answer 1

it is used for cleaning purposes like cleaning bathrooms
it is used to keep pests out from the dustbins.it is thrown around them.
it is used as anti bacterial stops from spreading infections.this is the main reason it is thrown around the dustbins.

Answer 2

they can be used for 
1- Sanitation
2- Used in kitchen to disinfect surfaces and equipment
3- in laundry as detergents