In the reaction $4K_2Cr_2O_7 \xrightarrow{\text{heat}} 4K_2CrO_4 + 3O_2 + X$,identify $X$.

Determine the correct $(T)$ and incorrect $(F)$ statements from the following:
$(a)$ The $E^o$ for $MnO_4^- + 8H^+ + 5e^- \to Mn^{2+} + 4H_2O$ is $-1.52 \ V$.
$(b)$ $MnO_4^-$ oxidizes $I^-$ to $I_2$.
$(c)$ The color of $CrO_4^{2-}$ is yellow in the presence of $H^+$.
$(d)$ The color of $CrO_4^{2-}$ is yellow in the presence of $OH^-$.

Match Column $A$ with Column $B$:

Column $A$	Column $B$
$(1)$ Brass	$(a)$ $Ni$ $(60\%)$,$Cr$ $(40\%)$
$(2)$ Bronze	$(b)$ $Cu$ $(80\%)$,$Sn$ $(20\%)$
$(3)$ Cupronickel	$(c)$ $Cu$ $(90\%)$,$Sn$ $(10\%)$
$(4)$ Nichrome	$(d)$ $Cu$ $(70\%)$,$Zn$ $(30\%)$
	$(e)$ $Cu$ $(75-85\%)$,$Ni$ $(15-25\%)$

When copper turnings and concentrated $HCl$ are heated with copper sulphate,the compound formed is:

Select the salt whose aqueous solution is not green.

Indicate the steps in the preparation of:
$(i)$ $K_2Cr_2O_7$ from chromite ore.
$(ii)$ $KMnO_4$ from pyrolusite ore.