Which transition metal oxide among the following has electrical conductivity similar to that of copper?

The incorrect statement among the following is :-

Alkaline oxidative fusion of $MnO_2$ gives $A$ which on electrolytic oxidation in alkaline solution produces $B$. $A$ and $B$ respectively are:

$MnO_2$ when fused with $KOH$ and oxidised in air gives a dark green compound $X$. In acidic solution,$X$ undergoes disproportionation to give an intense purple compound $Y$ and $MnO_2$. The compounds $X$ and $Y$,respectively,are

In making gun-barrel,the steel used is

What is obtained when gold chloride is heated?