How many variables should be tested in order for the experiment to valid?

The drawing represents the movement of particles in a substance. what changes of state can this substance undergo

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?

The number at the end of an isotope’s name is the number.