4. What do the numbers in Carbon-12 and Carbon-14 represent?!

The number in C-12 and C-14 represent their atomic masses.

Explanation:

The number in C-12 and C-14 represent their atomic masses.

These two are the isotopes of carbon.

Isotopes of an element have same atomic number and different atomic masses due to different number of neutrons present.

An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus. All these three subatomic particles construct an atom.

All isotopes of carbon have same number of electrons and protons i. e, six

while C-14 has 8 neutrons and C-12 has six neutrons.

C-14 = 14-6 = 8

C-12 = 12-6 = 6

Thus sum of neutrons and protons is atomic mass that's why C-14 has 14 atomic mass (8+6=14) while C-12 has 12 atomic mass (6+6=12).