Choose the correct statements from the following A. Mn _ 2 O _ 7 is...

 All the metals except scandium form MO oxides, which are ionic. ${Mn}_{2}{O}_{7}$ is a covalent green oil. In vanadium there is gradual change from the basic ${V}_{2}{O}_{3}$ to less basic ${V}_{2}{O}_{4}$ and to amphoteric ${V}_{2}{O}_{5}$ . ${V}_{2}{O}_{4}$ dissolves in acids to give ${VO}^{2 +}$ salts. Similarly, ${V}_{2}{O}_{5}$ reacts with alkalies as well as acids to give ${VO}_{4}^{3 -}$ and ${VO}_{4}^{+}$ respectively. The well characterised $CrO$ is basic but ${Cr}_{2}{O}_{3}$ is amphoteric.

(A) ${Mn}_{2}{O}_{7}$ is green oil at room temperature.

(B) ${V}_{2}{O}_{4}$ dissolve in acids to give $V{O}^{2 +}$ salts.

(C) $CrO$ is basic oxide.

Hence option B is the answer,