$Fe$,$Co$ and $Ni$ have valuable catalytic properties in processes involving

Transition metals vary widely in their chemical reactivity. Explain this with examples or write about the reactivity of $3d$ series metals with acids.

The order of basic character for the monoxides of transition metals is . . . . .

The correct statement about $Cr^{2+}$ and $Mn^{3+}$ among the following is (Given,atomic numbers of $Cr=24$ and $Mn=25$)

$Cu^{2+}$ ions will be reduced to $Cu^{+}$ ions by the addition of an aqueous solution of

Given below are two statements:
Assertion $(A)$: All $Cu$ $(II)$ halides are known except the iodide.
Reason $(R)$: $Cu^{2+}$ oxidizes $I^{-}$ to $I_2$.
The correct answer is: