Question

In which reaction does the oxidation number of hydrogen change?

a.hcl (aq) + naoh (aq) → nacl (aq) + h2o (l)
b.2na (s) + 2h2o (l) → 2naoh (aq) + h2 (g)
c.cao (s) + h2o (l) → ca(oh)2 (s)
d.2hclo4 (aq) + caco3 (s) → ca(clo4)2 (aq) + h2o (l) + co2 (g)
e.so2 (g) + h2o (l) → h2so3 (aq)?

Answer 1

it changes in
b.2na (s) + 2h2o (l) → 2naoh (aq) + h2 (g)
H2 has oxidation number of 0 but 2H2O implies H has oxidication number of 4