Isotopes of an element contain different numbers of .

The enthalpy of formation of water is -285.8 kj/mol. what can be inferred from this statement?

200. ml of 3.00 m nacl solution is diluted to a final volume of 500. ml. what is the molarity of the final solution?

Aradio signal from a gps satellite take only about 0.067 seconds to reach a gps reciever. if the speed of light is about 300,000km/s, then approximately how far away is the reciever from from the satellite?