The oxide that gives \( \mathrm{H_2O_2} \) most readily on treatment with \( \mathrm{H_2O} \) is:
\( \mathrm{Na_2O_2} \)
\( \mathrm{PbO_2} \)
\( \mathrm{SnO_2} \)
\( \mathrm{BaO_2 \cdot 8H_2O} \)