5
8
12
22
Answer is Right!
Answer is Wrong!
The correct answer is B. 8.
The atomic number of an element is the number of protons in the nucleus of an atom of that element. The number of protons determines the chemical properties of an element. Oxygen has 8 protons in its nucleus, so its atomic number is 8.
Option A is incorrect because 5 is the atomic number of boron. Option C is incorrect because 12 is the atomic number of carbon. Option D is incorrect because 22 is the atomic number of titanium.