Question

Which of the following is a false statement about the isotopes carbon-12 (12C) and carbon-13 (13C)? Please choose the correct answer from the following choices, and then select the submit answer button. 12C and 13C have the same atomic weight. 12C and 13C have different numbers of neutrons. 13C has one more electron than 12C. 13C has more subatomic particles in its nucleus than 12C. 13C has the same atomic number as 12C.

Answer 1

Answer: 13C has one more electron than 12C

Explanation:

Atomic number : It is defined as the number of electrons or number of protons present in a neutral atom.

Thus, number of protons = number of electrons = atomic number = 6 (for carbon)

Mass number is the number of the entities present in the nucleus which is the equal to the sum of the number of protons and electrons.

Mass number = Number of protons + Number of neutrons  

For C-12 , 12 = 6 +  Number of neutrons ,  Number of neutrons = 6

For C-13 , 12 = 6 +  Number of neutrons ,  Number of neutrons = 7

Atomic weight is the average of the masses of isotopes and hence is same for both C-12 and C-13.

Thus C-12 and C-13 have  different numbers of neutrons.