All atoms of the element potassium have 19 protons. One How many neutrons make up one of these potassium of the most stable types of potassium atoms has the atoms?
mass number 39.
A.19
B.20
C.38
D.58

When you jump from an elevated position you usually bend your knees upon reaching the ground. by doing this, you make the time of the impact about 10 times as great as for a stiff-legged landing. in this way the average force your body experiences is a) less than 1/10 as great. b) more than 1/10 as great. c) about 1/10 as great.d) about 10 times as great.

Give one example to show that when substances are mixed,it may result in a chemical or a physical change depending on the conditions.

The items in the following list are all units of matter. which is the smallest unit that retains the properties of the matter? a.) atom b.) compound c.) electron d.) element