In the reaction, $P$, $Q$, and $R$ respectively are:
$NaNO_2^{+}$ dilute $HCl$, $BF_3$, Cu + $NaNO_2$
$NaNO_3^{+}$ dilute $HCl$, $F_2$, Cu + $NaNO_3$
$NaNO_2^{+}$ dilute $HCl$, $HBF_4$, Cu + $NaNO_2$
$NaNO_2^{+}$ concentrated $HCl$, $F_2$, Cu + $NaNO_3$
