Among the metals Cr, Fe, Mn, Ti, Ba and Mg, the one that cannot be obtained by reduction of metal oxide by aluminium is (RPMT 2007)

Metals with very high melting points and the ones that can be obtained from their oxides can be extracted by the process of reduction from aluminium. Metals like chromium and manganese can be obtained by this process. However, reduction potential of Aluminium is more when compared with Magnesium. Hence, it will not be able to reduce Mg from its metal oxide by Aluminium. Therefore, the correct answer is option (d) Mg.