Which metal wire is used as a conductor of electricity?

The highest oxidation state of $Cr$ is:

Given below are two statements:
Statement $I :$ The $E^{\circ}$ value of $Ce^{4+} / Ce^{3+}$ is $+1.74 \, V$.
Statement $II :$ $Ce$ is more stable in $Ce^{4+}$ state than $Ce^{3+}$ state.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which of the following is a colourless ion?

Amongst the following,the lowest degree of paramagnetism per mole of the compound at $298 \ K$ will be shown by:

What should be the difference in atomic radii between two metal elements to form an alloy?