No, (NH₄)₂CO₃ reacts with NaCl as
(NH₄)₂CO₃ + 2NaCl \(\leftrightharpoons \) Na₂CO₃ + 2NH₄Cl
Because the products obtained Na₂CO₃ and NH₄Cl are highly soluble and the equilibrium will not shift in forward direction. That's why in the Solvay process, we cannot obtain sodium carbonate directly by treating the solution containing (NH₄)₂CO₃ with sodium chloride.

The Lewis structure of O₂ is  : \(\overset { .. }{ \underset { .. }{ O } } \)  ---  \(\overset { .. }{ O }\):
Oxygen atom carrying no charge has six electrons, so its oxidation number is zero. But oxygen atom carrying -1 charge has 7 electrons, so its oxidation number is -1.
Average oxidation number of each oxygen atom = \(\frac { 1 }{ 2 } \) 
\({ O }_{ 2 }^{ - }\)  = 2x = -1
\(\Longrightarrow \)  x = -\(\frac { 1 }{ 2 } \)

Peroxide ions react with water to form H₂O₂,
\({ O }_{ 2 }^{ 2- }\)  + 2 H₂ O  \(\longrightarrow \) 2OH^- + H₂O₂

Superoxides react with water to form H₂O₂ and O₂.
2\({ O }_{ 2 }^{ - }\)  + 2 H₂ O  \(\longrightarrow \) 2 OH^- + H₂ O₂ + O₂