Answer from cs61c-ca (christina capozzola 17003457) for Question 1
physical addresses are different from virtual addresses in that a physical address is assigned only one per space. the range is from 0 to some maxiumum. Also some of the physical address space is saved for use by the operating system and is not for processor use.

virtual addresses are used by the processor and assigned for use by the operating system. they start from zero but it is not the true zero of the memory. it's pseudo addresses.