$CrO_3$ is a/an ...

Consider the following reactions:
$K_2Cr_2O_7 + NaCl + H_2SO_4 \rightarrow CrO_2Cl_2 + \text{Side Products}$
$CrO_2Cl_{2(Vapour)} + NaOH \rightarrow B + NaCl + H_2O$
$B + H^+ \rightarrow C + H_2O$
The number of terminal $'O'$ atoms present in the compound $'C'$ is $..........$

Which of the following oxides is amphoteric?

Silver nitrate is mainly used

$K_2Cr_2O_7 + H_2O_2 \xrightarrow{H^{+}} $

The alloy that contains copper and $Zn$ is $x$ and the one that contains copper and $Ni$ is $y$. What are $x$ and $y$ respectively?