Among the following components of cement,which is present in the highest amount?

Which of the following cations has the lowest spin-only magnetic moment?

Which of the following has the highest paramagnetic character?

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.

Assertion $(A)$: Transition elements have higher enthalpies of atomization.
Reason $(R)$: Large number of unpaired electrons present in transition elements facilitate strong interatomic interaction and strong bonding between atoms.

Which of the following represents the correct order of atomic radii (metallic radii) for the given transition elements?