$Cu^{2+}$ aqueous solution has . . . . . . colour.

Write a note on halide compounds of transition elements.

Choose the correct statements from the following:
$A$. $Mn_2O_7$ is an oil at room temperature.
$B$. $V_2O_4$ reacts with acid to give $VO^{2+}$ ions.
$C$. $CrO$ is a basic oxide.
$D$. $V_2O_5$ does not react with acid.
Choose the correct answer from the options given below:

Assertion : Coloured cations can be identified by borax bead test.
Reason : Transparent bead $(NaBO_2 + B_2O_3)$ forms coloured bead with coloured cation.

Assertion: $KMnO_4$ is purple in colour due to charge transfer.
Reason: There is no electron present in $d$-orbitals of Manganese in $MnO_4^-$.

In which compound does chromium have a $+6$ oxidation state?