Boiling $CuCl_2$ with $Cu$ in concentrated $HCl$ gives:

In making gun-barrel,the steel used is

Which of the following mixtures forms chromic acid?

When a manganese $(Mn^{II})$ salt is fused with a mixture of $KNO_3$ and solid $NaOH$,what will be the oxidation state of $Mn$ after it changes from $+2$?

Cigarette or gas lighter is made up of

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