Why does sodium have the symbol na in the periodic table? and the other atoms in the periodic table with there symbol being other letters instead of the one that is in the word. and if you can for the real names of all the atoms with different symbols.

3. how much energy in joules is required to evaporate .0005 kg of liquid ammonia to vapor at the same temperature? 4. how much energy ( in megajoules ) is given up by .75 kg of water at 0c when it freezes to form ice at 0c? 5. explain how heat works between and at critical temperatures?