The neutral atoms Calcium and Argon both have a mass of 40. Calcium has 20 electrons and Argon has 18 electrons. How can they have the same mass

The layers of earth are based on what two sets of characteristics?

Democratic vs democratic whats the difference? ?

Where was oil production at its highest in the 1980s and still remains important to the russian economy? central asia the ural mountains russian siberia the caucasus region