List 2 physical properties that can be used to differentiate between a Cu ( before 1982) penny and a Zn (after 1982) penny.

This is a characteristic of the elements in the periodic table that shows a pattern. it may increase or decrease across or down the table.

You are making a solution of calcium chloride dissolved in water. you add solid, stir, and it dissolves. you add just a spatula tip full, stir, and the solid does not dissolve. how could you describe the solutions before and after adding the spatula tip amount

Which of the following would be an accurate picture of the earth during the summer time of the northern hemisphere?