The conductivity and appearance of $CrO_2$ are like metallic $Cu$.

Identify the correctly matched pairs:
$(i)$ $TiO_2$ - pigment industry
$(ii)$ $MnO_2$ - dry battery cells
$(iii)$ $Cu/Ni$ alloy - $UK$ 'copper' coins

Which of the following oxides is amphoteric?

When a mixture of $NaCl$,$K_{2}Cr_{2}O_{7}$ and conc. $H_{2}SO_{4}$ is heated in a dry test tube,a red vapour $(X)$ is evolved. This vapour $(X)$ turns an aqueous solution of $NaOH$ yellow due to the formation of $Y$. $X$ and $Y$,respectively,are

Which of the following is incorrect about $K_{2}Cr_{2}O_{7}$?

The colour of the bead in the borax bead test is mainly due to the formation of: