What can we use to determine the relative age of two rocks

Nuclear fusion is the source of energy for stars. besides hydrogen, which other element is most likely also common in stars?

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?

Which statement explains why the bonds between non metals tend to be covalent? the bonds are found to be nondirectional they have large differences in electronegativity they have small differences in electronegativity they have ions that produce an electrostatic pull