Do protons determine isotopes

What rule is used to determine how many covalent bonds an element can form? a. the number of covalent bonds is equal to six c the number of covalent bonds is equal to five minus the group number plus the group number b. the number of covalent bonds is equal to eight d. none of the above minus the group number select the best answer from the choices provided

What is a main difference between a mixture and a pure substance? a mixture is only a liquid, but a pure substance can be in any state. a mixture looks the same throughout, but a pure substance does not.1 a mixture can vary in composition, but a pure substance has a set composlo a mixture can be made up of a single compound, but a pure substance car

How does carbon monoxide pose the greatest threat to humans? a. it can be produced by wood fires. b. it can be produced by home furnaces. c. it is produced by acid rain. d. it is produced by modern automobiles.