Statement 1: The lowest oxide of a transition metal (say, chromium, atomic number 24) is basic whereas the highest oxide is usually acidic.

Statement 2: ${\mathrm{Cr}}_2{\mathrm{O}}_3$ is amphoteric in nature.

Both are correct statements but statement 2 is not correct explanation of statement 1. As the oxidation states of metals increase, the electronegativity values also increase. As a result the difference of electronegativities between metal and oxygen decreases and, therefore, acidic character of oxides increase.