what are critical size and radiation hazards??

i want to knoe about elecromagnetic radiation.properties of elecromagnetic waves, elecromagnetic spectrum, uses of elecromagnetic radiations, photoelectric effect, lasers..

i want to know what is  molarity??

i want to knoe what is-

heat of formation

heat of vaporization

heat of fusion

heat of transition

...i want to knoe in which state they occur....

i also want to know wt is equivalent weight.......

pls send the answer to me in shraddha_771981@rediffmail.com coz i dun really knoe how to see the answers here....

thanx..

can you tell me more about vectors??