Question

Which one of the following is more acidic?
(a) $N{{a}_{2}}O$
(b) $MgO$
(c) $A{{l}_{2}}{{O}_{3}}$
(d) $CaO$

Answer 1

Hint: The acidic nature of the compound depends upon its metallic character. More the metallic character, lesser is the acidic character and vice-versa. So, identify decompounds having the least metallic character, you will get to know about the compound having the highest acidic character.

Complete step by step answer:
- First, let’s discuss what acid is. An acid is a substance, which has a strong tendency to lose the proton.
- In other words, acid can also be defined as those substances which have a strong tendency to accept electrons from the electron donor species.
- In terms of the metallic character, the substances which possess the least metallic character, are the strongest acids and vice-versa.

Now consider the statement as;
We will find the acidic character of the given compounds on the basis of their metallic character. The more the metallic character of the compound, the lesser is the acidic character of the compound, and if the metallic character of the compound is less, then more is the acidic character of the compound.
The order of the metallic nature of the given compounds is as:
$N{{a}_{2}}O>CaO>MgO>A{{l}_{2}}{{O}_{3}}$
so, thus, the increasing order of the acidic character of the given compounds is as:
$N{{a}_{2}}OHence, $A{{l}_{2}}{{O}_{3}}$ is the most acidic of all the given compounds.
So, the correct answer is “Option C”.

Note: Don’t get confused in the acid and the base. Acids are those substances that have strong non-metallic characters Whereas, on the other hand, the base is those substances that have strong metallic characters.