3)
Atoms of which two elements have a combined total of 23 protons?
A) Sodium, Na, and magnesium, Mg
B) Boron, B, and carbon, C
C) Copper, Cu, and zinc, Zn
D) None of these

Option A is correct. The atoms of which two elements have a combined total of 23 protons are Sodium and magnesium

The proton of an element is also known as its atomic number.

Given

Total number of protons = 23 protons

We need to find two elements whose atomic numbers sum up to 23.

Atomic number of sodium = 11 (This means that it contains 11 protons)

Atomic number of magnesium = 12

Sum of their atomic number = 11 + 12 = 23

This means that the atoms of which two elements have a combined total of 23 protons are Sodium and magnesium.

Learn more here: link