Question

what is the mass number of a carbon isotope that has 6 protons and 7 neutrons?
○ 6 amu
○ 7 amu
○ 13 amu
○ not enough information to calculate

Explanation:

Step1: Recall mass number definition

Mass number = number of protons + number of neutrons

Step2: Substitute given values

$\text{Mass number} = 6 + 7$

Step3: Calculate the sum

$\text{Mass number} = 13$

Answer:

13 amu