Please help me if you can

Can someone me with questions 15 to 17 plz.

How do you identify the anode on a power source such as a battery? how do you identify the cathode? how are terms anion and cation?

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