Which reaction doesn't get back to reactants ( chemical equilibrium question):

1)NaOH + HCL = NaCl + H2O
2) AgNO3 + BaCl2 = AgCl + Ba(NO3)2
3) 2Cu(NO3)2 = 2 CuO + 4NO2 + O2
4) CO + H2O = CO2 + H2 (closed container)

Question

Which reaction doesn't get back to reactants ( chemical equilibrium question):

1)NaOH + HCL = NaCl + H2O
2) AgNO3 + BaCl2 = AgCl + Ba(NO3)2
3) 2Cu(NO3)2 = 2 CuO + 4NO2 + O2
4) CO + H2O = CO2 + H2 (closed container)

rvc · Answer

Water (H2O) and common Salt (NaCl) when mixed if produced a strong acid and strong base then our lives would be difficult :) what do you think is the ans?

trojanpoem · Answer

I think (1), (2), (3) < not sure about  (3)

rvc · Answer

i think about the first one only :/

trojanpoem · Answer

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trojanpoem · Answer

My  problem is No2 and Cuo ? will they get back or no.

rvc · Answer

@Hoslos please help 
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rvc · Answer

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anonymous · Answer

I think it will be B.
Basically, for a reaction to be of a reverse character, there is a need for both reactants and products to be in aqueous states.
As for B, a solid AgCl is formed and cannot react with Ba(NO3)2 to go back to the original aqueous reactants.