2 mole of ideal gas at 27^oC temperature is expanded reversibly from 2 lit. to 20 lit. Find entropy change. (R = 2 cal/mol K)

Change in enthalpy for reaction,

2H₂O_2(l) $$ \to $$ 2H₂O_(l) + O_2(g)

if heat of formation of H₂O_2(l) and H₂O_(l) are $$-$$188 and - 286 kJ/mol respectively, is

When 1 mol of gas is heated at constant volume temperature is raised from 298 to 308 K. Heat supplied to the gas is 500 J. Then which statement is correct ?

PbO₂  $$ \to $$ PbO; $$\Delta $$G₂₉₈ < 0
SnO₂ $$ \to $$ SnO;  $$\Delta $$G₂₉₈ > 0

Most probable oxidation state of Pb and Sn will be