I intend to purchase an air conditioner for my room 16 Ft X 12 Ft .?

Its Good to consider the size and space of your room as well as the environment. I suggest you to ask some help from professionals, centers, or sites that gives you good tips, and offers better quality services like famousacandheat..

The kelvin temp changes from 300 to 270 so Charles' Law would dictate that the room would shrink by 10% in volume if it were flexible. Since the room does not change in either volume or pressure logic dictates that 10% of the original volume must flow into the room. 16x12x12x(0.1) This assumes that the inflowing air does not change temp, that the outside air was already at -3 C, If, however, the outside air was at 27 C and had to cool down also then 11.1% of the room's original volume would have to flow in so that the incoming air could also shrink by 10%.

You can chech these articles for room size and comparison of split and window ACs:

http://indiahometips.com/buying-ac.html

http://indiahometips.com/split-vs-window-ac.html