11) What is it about carbon-12, carbon-13, and carbon-14 that makes them all carbon?

A) They all have the number of protons plus neutrons that is characteristic of carbon.

B) They all have the number of protons that is characteristic of carbon.

C) They all have the number of neutrons that is characteristic of carbon.

D) They all are radioactive.

E) They all are elements.

12) You have a substance and begin a set of experiments in which you break it down into other substances through chemical reactions. After a few successive reactions, you discover a set of products that can’t be broken down further, no matter what type of chemical reaction you attempt. These substances are:

A) protons.

B) elements.

C) neutrons.

D) electrons.

E) isotopes.

13) Atoms with eight electrons in their outer shells tend to:

A) form covalent bonds.

B) form ionic bonds.

C) be chemically reactive.

D) be stable and unreactive.

14) Which of the following results from the making of a bond?

A) Atoms become more reactive.

B) Molecules are broken down.

C) Electrons are destroyed.

D) Atoms become more stable.

15) For an atom to be considered an ion:

A) protons can outnumber neutrons.

B) protons can outnumber electrons.

C) neutrons can outnumber protons.

D) protons equal electrons.

16) As the difference in the electronegativity between atoms forming a chemical bond increases, the:

A) less polar the molecule.

B) more polar the molecule.

C) more stable the molecule.

D) more symmetrical the molecule.

17) A polar covalent bond results when:

A) two atoms share electrons equally.

B) two atoms of the same element are sharing electrons.

C) one of the atoms sharing electrons is more electronegative than the other atom.

D) two atoms sharing electrons are equally electronegative.

18) An atom will react with other atoms only until:

A) it has completely filled its outermost energy level.

B) it has less stability.

C) all of its inner orbitals have been filled.

D) it forms four covalent bonds

19) The naturally occurring helium atom is chemically inert because:

A) its outermost shell is filled with electrons.

B) its nucleus is filled with two neutrons.

C) it has the most protons that it could ever carry.

D) it has all of the shared electrons it could ever have.

20) Nonpolar molecules develop when:

A) shared electrons are not shared equally.

B) both atoms have similar electronegativity.

C) one atom is much more electronegative than the other.

D) electrons are completely transferred from one atom to another.