What charge does an atom that has lost electrons have?​

Water (2510 g ) is heated until it just begins to boil. if the water absorbs 5.09×105 j of heat in the process, what was the initial temperature of the water?

(apex) when a cup of water is dropped, as the cup falls, the water in the cup falls out true or false?

When a spring is compressed, the energy changes from kinetic to potential. which best describes what is causing this change?