Windows 7 will use the complete 8GB RAM, however each process is normally limited to 2GB.
This only ever applied to Intel IA-32 processors with memory controllers that used bank switching. Basically everything up until P4.
Since W10 the per process memory limit has been at least 8TB.
my original question still stands: why does System Properties show system type x86 (not able to run 64-bit OS) when Microsoft data sheet says that processor is able to do that?
x86 is the common name for Intel's 8086 CPU architecture. Nowdays x86 implies 32bit CPU (whereas x64 implies 64bit CPU) so System Properties is a little misleading.
Pretty much all Intel mobile/desktop CPU's released since ~2007 are 64bit (except Atom). Certainly the i5.