Question

Which of the following oxides is most acidic?
(A) $A{l_2}{O_3}$
(B) $Si{O_2}$
(C) ${P_2}{O_5}$
(D) $S{O_3}$

Answer 1

Hint : The given options are the oxides and belong to the same period. The acidic oxides of the same period follow a basic trend in the periodic table. We also know that acidic strength depends on several factors such as oxidation states and many more.

Complete Step By Step Answer:
First, we will understand some basic things about the acidic oxides. Acidic oxides are the oxides which when combined with water give an acid. There are many ways to determine or predict the oxides whether they are acidic or basic. But in general, we follow a basic rule that the type of oxide depends on the electropositive character of the metal. So, according to the rule, the more electropositive character of the oxide’s central atom, the more basic will be the oxide and the more electronegative the central atom of the oxide, the more acidic the oxide will be.
Now we are back to our question: we have given the following oxides in the options. The oxides are $A{l_2}{O_3},Si{O_2},{P_2}{O_5}$ and $S{O_3}$ . We know that the central metal atom belongs to the same period. So, according to the trends, the acidic strength of oxides increases when we move from left to right in the periodic table. So, according to the trend correct order of acidic strength will be $A{l_2}{O_3} < Si{O_2} < {P_2}{O_5} < S{O_3}$ . So, we can conclude that $S{O_3}$ is most acidic.
Therefore, the correct option is (D).

Note :
We can also figure out the most acidic oxide using the electronegativity character of the central metal atom. As we know that electronegativity increases moving left to right in the periodic table. The more electronegative character of the central atom more acidic the oxide.