Should I install SQL Server 64 bit or 32 bit
32 bit OS and 64 bit Processor


If the OS is 32-bit, then your applications would have to be 32-bit as well.


  64 bit OS and 32 bit Processor


You cannot install a 64-bit OS on a 32-bit processor, so this isn't relevant


  when to install SQL Server 64 bit package and when to install 32 bit
  package


SQL Server 2008 R2 is no longer a supported platform, and modern, supported versions of SQL Server are only 64-bit, so the question itself is kind of irrelevent - you should not be installing unsupported versions of SQL Server, however, if you are required to:


On a 32-bit OS, you can only install the 32-bit version of SQL Server.
If you have a 64-bit OS (by definition on a 64-bit processor) then you should install the 64-bit version of SQL Server to take full advantage of available resources.