3 what are the differences between 32 bit and 64 bit os's

A 32-bit system can access 2³² memory addresses, i.e 4 GB of RAM or physical memory ideally, it can access more than 4 GB of RAM also. A 64-bit system can access 2⁶⁴ memory addresses, i.e actually 18-Quintillion bytes of RAM. In short, any amount of memory greater than 4 GB can be easily handled by it.