(d)
${Na}_{2}S_{4}O_{6}$ is
[image:3_image5.emf]
The two S atoms which are linked to each other have 0 oxidation number. The oxidation number of other two S-atoms can be calculated as
$2x + 2 \times 0 + 6 \times - 2 = - 2$
$2x = 12 - 2 = 10$
$x = + 5$