Which of the following may be colourless?

$A$ chloro compound of vanadium has a spin-only magnetic moment of $1.73 \ BM$. This vanadium chloride has the formula:

The correct statement$(s)$ about $Cr^{2+}$ and $Mn^{3+}$ is(are)
[Atomic numbers of $Cr = 24$ and $Mn = 25$]
$(A)$ $Cr^{2+}$ is a reducing agent
$(B)$ $Mn^{3+}$ is an oxidizing agent
$(C)$ Both $Cr^{2+}$ and $Mn^{3+}$ exhibit $d^4$ electronic configuration
$(D)$ When $Cr^{2+}$ is used as a reducing agent,the chromium ion attains $d^3$ electronic configuration

The number of $d$-electrons in $Cr^{3+}$ ion $(Z=24)$ is

Determine whether the following statements are True $(T)$ or False $(F)$:
$(a)$ An element or its ion that does not have a completely filled $d$-orbital is considered a transition element.
$(b)$ $Sc$ is a transition element.
$(c)$ $Zn$ is a transition element.
$(d)$ The energy difference between $(n-1)d$ and $ns$ orbitals is high.

Which of the following transition metal ions has a magnetic moment of $3.87 \ BM$?