Question

atom 1 has mass=12 protons=6
atom 2 has mass= 14 electrons=6
are these atoms isotopes of each other or different elements?
1 different elements - ar & ca
2 different elements - mg & si
3 isotopes of carbon
4 isotopes of magnesium

Explanation:

Step1: Recall element - identity rule

The number of protons determines the element. Atom 1 has 6 protons, so it is carbon. In a neutral atom, the number of electrons equals the number of protons. Atom 2 has 6 electrons, so it also has 6 protons and is carbon.

Step2: Recall isotope definition

Isotopes are atoms of the same element with different mass - numbers. Atom 1 has a mass - number of 12 and Atom 2 has a mass - number of 14. Since they are both carbon with different mass - numbers, they are isotopes.

Answer:

C. Isotopes of Carbon