Woodrow Wilson was referring to the liberal idea of the economic market when he said that the free enterprise system is the (much) efficient economic system.
With demand paging, a page is brought into memory only when a location on that page is actually referenced during execution. With pre-paging, pages other than the one demanded by a page fault are brought in. The selection of such pages is done based on common access patterns, especially for secondary memory devices.
The filled orbitals are (1s)2, (1s)2, (2s)2, (2s)2. The half-filled orbitals are (2px) and (2py). Since it posses 2 unpaired electrons, it is Paramagnetic in nature.