Hypophosphorous acid is

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

How many $H-$ atoms are directly bonded to the phosphorus atom in hypophosphorous acid?

Which colorless gas has a smell like rotten fish?

Which substance is used as a smoke screen in warfare?

$NH_3 + O_2 \xrightarrow[500 \ K]{Pt} W + H_2O$
$W + O_2 \rightleftharpoons X$
$X + H_2O \rightleftharpoons Y + W$
Which of the following statements is correct?