The frequency of electromagnetic radiation is measured in waves/second, or?

pure water does not conduct electricity very well. however, when certain substances are dissolved in water, the solution does conduct electricity. you can make a simple device that shows how well a solution conducts electricity. this device uses a flashlight bulb to indicate how well the solution conducts electricity. the better the solution conducts electricity, the brighter the bulb will glow.

explanation:

first one is the correct answer

the answer is definitely c.

it's c. elements are placed in rows based on how may valencies electrons have.