Question
Which of the following are basic oxides?
$$M{n_2}{O_7},{V_2}{O_3},{V_2}{O_5},CrO,C{r_2}{O_3}$$
A.
$$M{n_2}{O_7}\,{\text{and}}\,{V_2}{O_3}$$
B.
$${V_2}{O_3}\,{\text{and}}\,CrO$$
C.
$$CrO\,{\text{and}}\,C{r_2}{O_3}$$
D.
$${V_2}{O_5}\,{\text{and}}\,{V_2}{O_3}$$
Answer :
$${V_2}{O_3}\,{\text{and}}\,CrO$$
Solution :
In case of transition metal oxides, the oxides with metals in lower oxidation states are basic in nature.
$$O.S.$$ of $$Mn$$ in $$M{n_2}{O_7} = + 7;V$$ in $${V_2}{O_3} = + 3;V$$ in $${V_2}{O_5} = + 5;Cr$$ in $$CrO = + 2;Cr$$ in $$C{r_2}{O_3} = + 3$$
Thus in $${V_2}{O_3},CrO$$ and $$C{r_2}{O_3}$$ transition metal ion is in lower oxidation state but $$C{r_2}{O_3}$$ is amphoteric in nature. Hence $${V_2}{O_3}$$ and $$CrO$$ are basic in nature.