13. how many protons are present in total in a carbon atom?
(a) there are always twelve.
(b) there are always six.
(c) it depends on the isotope.
(d) there are always four.

14. of the following, which molecule is most polar? (the electronegativities of the atoms are as follows: chlorine 3.0, boron 2.0, hydrogen 2.1, oxygen 3.5, carbon 2.5, and bromine 2.8.)

The answer to your question is below

13.- b

Explanation:

13. How many protons are present in total in a carbon atom?

(a) There are always twelve.  No, atomic mass of Carbon is 12 but the number of protons is half the atomic mass (6).

(b) There are always six.  The answer is correct. Carbon's atomic number is 6, that means that it has 6 protons.

(c) It depends on the isotope.  It's wrong, depends on the isotope the number of neutrons but not the number of protons.

(d) There are always four.  No, 4 is the number of protons of Beryllium.

14. Of the following, which molecule is most polar? (The electronegativities of the atoms are as follows: chlorine 3.0, boron 2.0, hydrogen 2.1, oxygen 3.5, carbon 2.5, and bromine 2.8.)

Oxygen, because of these elements is the one with the highest electronegativity.

c-14 is carbon-14, or radiocarbon.   it is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons.