Which among the following elements does $NOT$ exhibit ferromagnetic properties?

Identify the weakest base from the following.

Which statement is incorrect from the following?

What are interstitial compounds? Why are such compounds well known for transition metals?

Assertion : Cuprous ion $(Cu^+)$ has unpaired electrons while cupric ion $(Cu^{2+})$ does not.
Reason : Cuprous ion $(Cu^+)$ is colourless whereas cupric ion $(Cu^{2+})$ is blue in the aqueous solution.

Which of the following elements has the maximum first ionization potential?