A single atom of an element has 11 protons, 11 electrons, and 12 neutrons. Which element is it?

A. V

B. Na

C. Mg

D. Se

A. V is Vanadium and it has 23 electrons, so it couldn't be your answer.

B. Na is sodium and has 11 electrons, so it is your answer

C. Mg is Magnesium and it has 12 electrons, so it couldn't be your answer either.

D. Se is Selenium and it has 34 electrons, so it couldn't be your answer.

So your answer is B.

Answer;

Sodium (Na)

A single sodium atom has 11 protons, 11 electrons, and 12 neutrons.

Explanation;

For any neutral atom, the number of protons is the same as the number of electrons. If an atom loses or gains electrons, it is called an ion.

A sodium atom contains 11 protons, so its atomic number is 11. Mass number is the total of the protons and neutrons together, thus sodium has a mass number of 23.