In addition too properties of elements, list at least two other things or events that are periodic

If a 12-v battery is connected to a circuit that has a current of 3.0 a, what is the total resistance in the circuit? 36 ohms 4 ohms 0.25 ohms

Which of the following signs of a chemical reaction are observed in the reaction of potassium with water? precipitate formed temperature change smell produced gas produced color change

Significant figures are digits read directly from the measuring instrument plus one more digit, which is __ by the observer.