Which of the following pairs of oxides is amphoteric in nature?

The number of ions from the following that have the ability to liberate hydrogen from a dilute acid is. . . . . . . .$Ti^{2+}, Cr^{2+}, V^{2+}$

Vanadium $(III)$ oxide $(V_2O_3)$ is a strong:

Discuss the catalytic properties of transition elements.

The electronic configuration of $Cu(II)$ is $3d^9$ whereas that of $Cu(I)$ is $3d^{10}$. Which of the following is correct?

Identify the correct order of oxidizing power.