Choose the correct statement$(s)$ among the following.
$A$. $SnCl_2 \cdot 2 H_2O$ is a reducing agent.
$B$. $SnO_2$ reacts with $KOH$ to form $K_2[Sn(OH)_6]$.
$C$. $A$ solution of $PbCl_2$ in $HCl$ contains $Pb^{2+}$ and $Cl^{-}$ ions.
$D$. The reaction of $Pb_3O_4$ with hot dilute nitric acid to give $PbO_2$ is a redox reaction.

Which of the following reactions gives nitrogen $(II)$ oxide $(NO)$ as one of the products?

When copper metal is treated with cold and dilute nitric acid, it forms

The gas which is absorbed by ferrous sulphate solution giving blackish brown colour is

$A$ $p$-block element $(E)$ and hydrogen form a binary cation $(EH_{x}^{+})$, while $EH_{3}$ on treatment with $K_{2}HgI_{4}$ in alkaline medium gives a precipitate of basic mercury$(II)$amido-iodine. Given below are first ionisation enthalpy values $(kJ \ mol^{-1})$ for the first element of each group $13, 14, 15$, and $16$. Identify the correct first ionisation enthalpy value for element $E$.

When a lightning flash is produced,which gas is primarily formed?