Which of these elements is a metal? a. hafnium (hf) b. radon (rn) c. silicon (si) d. sulfur (s) e. selenium (se)

The answer is A. Hafnium

Option (A) is the correct answer.

Explanation:

Substances or elements which lose electrons are known as metals whereas elements which gain electrons are known as non-metals.

For example, electronic configuration of hafnium is . It is a transition metal as it has incompletely filled d-orbital so, it will lose electrons to attain stability.

Electronic configuration of radon is . Since it is a noble gas it has completely filled orbitals so, it will neither lose nor gain electrons.

Electronic configuration of silicon is and it is a non-metal. So, it will gain electrons to complete its octet.

Electronic configuration of sulfur is and it is a non-metal. So, it will gain electrons to complete its octet.

Electronic configuration of selenium is and it is a non-metals. So, it will gain electrons to complete its octet.

Hence, we can conclude that out of the given options hafnium (Hf) is the element which is a metal.