The correct sequential order of the reagents for the given reaction is
$\mathrm{HNO}_{2}, \mathrm{Fe} / \mathrm{H}^{+}, \mathrm{HNO}_{2}, \mathrm{KI}, \mathrm{H}_{2} \mathrm{O} / \mathrm{H}^{+}$
$\mathrm{HNO}_{2}, \mathrm{KI}, \mathrm{Fe} / \mathrm{H}^{+}, \mathrm{HNO}_{2}, \mathrm{H}_{2} \mathrm{O} /$ warm
$\mathrm{HNO}_{2}, \mathrm{KI}, \mathrm{HNO}_{2}, \mathrm{Fe} / \mathrm{H}^{+}, \mathrm{H}_{2} \mathrm{O} / \mathrm{H}^{+}$
$\mathrm{HNO}_{2}, \mathrm{Fe} / \mathrm{H}^{+}, \mathrm{KI}, \mathrm{HNO}_{2}, \mathrm{H}_{2} \mathrm{O} /$ warm
