Question

Which of the following oxide is least basic?

• A. $CrO$
• B. $C{r}_2{O}_3$
• C. $Cr{O}_3$
• D. $C{r}_2{O}_4$

Answer 1

The correct option is C $Cr{O}_3$

solution:

$CrO=Basic$

$C{r}_2{O}_3=Amphoteric$

$C{r}_2{O}_4=Amphoteric$

$Cr{O}_3=Acidic$

Reason :Generally, the electropositive character of oxide's central atom will decide whether it will be basic or acidic. The more electropositive the central atom the more basic the oxide. The more electronegative the central atom the more acidic the oxide .In general ,electropositive character increases from right to left in periods and increases down the column. Chromium is a d block element, and d block elements exhibit wide variety of oxidation numbers. The higher the oxidation number the more acidic is the corresponding oxide and chromium is an example for this.

least basic or most acidic

hence the correct option: C