Question

which of the following elements has only 12 protons?
zn
o
c
mg
none of the above

Explanation:

Step1: Recall proton number (atomic number) of each element.

• Zn (Zinc) has atomic number 30, so 30 protons.
• O (Oxygen) has atomic number 8, so 8 protons.
• C (Carbon) has atomic number 6, so 6 protons.
• Mg (Magnesium) has atomic number 12, so 12 protons.

Step2: Compare with the required 12 protons.

Mg has atomic number 12, meaning it has 12 protons.

Answer:

D. Mg (assuming the options are labeled A: Zn, B: O, C: C, D: Mg, E: none of the above; if labels differ, adjust to the correct label with "Mg" as the option text)