Question

Why do non-metals not react with acids?
(A) They have a very high melting point and boiling point
(B) They lose electrons readily
(c) They are unreactive
(D) They gain electrons readily

Answer 1

Hint: An element loses or gains electrons in the outermost shell to complete its octet. As the elements that have fully filled the octet will be stable chemically. Any substance that reacts in an acidic medium gives out ${H^ + }$ ion.

Complete step by step answer:
When a substance reacts with the acid, the ${H^ + }$ ions. Generally the elements except the noble gases will either lose electrons or gain electrons in order to fill its octet.
Let us consider two to explain the concept well,
Case I: If an element has 2 electrons in its outermost shell (p orbital) it would prefer to lose the 2 electrons than gaining 4 electrons in order to form stable compounds.

Case II: If an element has 5 electrons in its outermost shell, this atom would prefer to gain one electron rather than losing 5 electrons in order to attain the stability.
The elements that readily lose electrons in order to fulfill its octet are called electron donors (case I) and the elements that readily gain or accept electrons are called electron acceptors (case II).
Most metals are electron donors and non-metals are electron acceptors.

Option A is "They have a very high melting and boiling point". The melting and boiling point depends on electropositivity. Yes the option is true, but this option does not have connection with this question. Thus this option is not the correct answer.

Option B is "They lose electrons readily". Firstly, this statement itself is wrong as in the above discussion, we saw mostly non-metals are electron acceptors. Thus, this is not the correct option.

Option C is "unreactive". Noble gases, which is unreactive and they are non-metals. We can say it is an exception when compared to other non-metals. If non-metals are unreactive then, it won't react with any other elements, compound exactly like noble gases. Thus option C is incorrect.

Option D is "They gain electrons readily". We know that any substance when it reacts with acid gives out ${H^ + }$ ions, since non-metals are electron acceptors, it prefers to gain an electron in order to attain stability rather than losing electrons.
So, the correct answer is “Option D”.

Note: Non-metals won't react with dilute acids at any point, but there are some exceptions where non-metals react with strong acids like $HN{O_3}$ etc. In general non-metals don't react with acids especially with dilute acids as it is an electron acceptor. Understand case I and II thoroughly for better understanding of the concept behind this question.