The correct order of acidic strength of oxides of nitrogen is

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

Which reaction$(s)$ among the following produce dinitrogen?
$1. NH_4Cl(aq) + NaNO_2(aq) \longrightarrow$
$2. NH_2CONH_2 + 2H_2O \longrightarrow$
$3. Ba(N_3)_2 \longrightarrow$
$4. NH_4Cl + Ca(OH)_2 \longrightarrow$

Which of the following combines with $Fe(II)$ ions to form a brown complex?

Match the following List-$I$ (Acid) with List-$II$ (Reagents used for preparation):
| List-$I$ (Acid) | List-$II$ (Reagents used for preparation) |
| :--- | :--- |
| $A. H_3PO_2$ | $I. \text{Red } P_4 \text{alkali}$ |
| $B. H_4P_2O_5$ | $II. \text{White } P_4 \text{alkali}$ |
| $C. H_3PO_4$ | $III. PCl_3; H_3PO_3$ |
| $D. H_4P_2O_7$ | $IV. P_2O_5; H_2O$ |
| | $V. H_3PO_4; \Delta$ |

Describe the preparation,properties,and structures of oxides of nitrogen.