What element has an atomic mass 4?

Great amounts of electromagnetic energy from our sun and other bodies in space travel through space. which is a logical conclusion about these electromagnetic waves? their energy must be very their frequency must be very low these waves can travel without a medium they only travel through a vacuum of space

If two objects at different te,peraure are in contact with each other what happens to their temperature

Asubstance is a good conductor of electricity which of the following best explains a probable position of the substance in a periodic table