Question

Consider the following designation for an isotope of phosphorus-31: A Z P ""A"" is the mass number, ""Z"" is the atomic number, and ""X"" is the chemical symbol of the element. What numbers should be used for the letter ""A"" and the letter ""Z""? A. A = 31, Z = 15 B. A = 30, Z = 15 C. A = 15, Z = 31 D. A = 31, Z = 17

Answer 1

A is 31 (A.)

Z is 15 (C.)

Step-by-step explanation:

Phosphorus is element number 15, which means it has 15 protons in the nucleus: the "atomic number." Phosphorus-31 tells us the atomic mass is 31.