The catalytic activity of the transition metals and their compounds is ascribed to their

Which one of the following sets correctly represents the increase in the paramagnetic property of the ions?

The spin-only magnetic moment value of the ion among $Ti^{2+}$,$V^{2+}$,$Co^{3+}$,and $Cr^{2+}$ that acts as a strong oxidizing agent in aqueous solution is .......... $BM$ (nearest integer).
(Given atomic numbers: $Ti = 22, V = 23, Cr = 24, Co = 27$)

Match the properties given in List-$I$ with the metals given in List-$II$:

List-$I$ (Property)	List-$II$ (Metal)
$(A)$ Element that can show $+8$ oxidation state	$(1)$ $Mn$
$(B)$ $3d$ series element that can show up to $+7$ oxidation state	$(2)$ $Cr$
$(C)$ $3d$ series element with maximum melting point	$(3)$ $Os$
	$(4)$ $Fe$

Which of the following pairs has a similar magnetic moment?

Which of the following oxides is white but becomes yellow on heating?