Question

1. all oxygen atoms have eight protons, and most have eight neutrons as well. what is the mass number of an oxygen isotope that has nine neutrons? what is the name of this isotope?

Explanation:

Step1: Recall mass number formula

Mass number ($A$) is the sum of protons ($p$) and neutrons ($n$), so $A = p + n$.

Step2: Identify protons and neutrons

Oxygen has 8 protons ($p = 8$), and this isotope has 9 neutrons ($n = 9$).

Step3: Calculate mass number

Substitute into the formula: $A = 8 + 9 = 17$.

Step4: Name the isotope

Isotopes are named with the element name and mass number, so it's oxygen - 17.

Answer:

The mass number is 17, and the isotope is oxygen - 17.