When hydrochloric acid is added to cobalt nitrate solution at room temperature, following reaction takes place and the reaction mixture becomes blue. On cooling the mixture it becomes pink

[Co(H2O)6]3+(Pink)(aq)+4Cl-(aq)⇌[CoCl4]2-(Blue)(aq)+6H2O(l)

On the basis of information given above, mark the correct answer

1. H>0 for the reaction

2, H<0 for the reaction

3. H=0 for the reaction

4. The sign of H cannot be predicted on the basis of the given information.

Hint: For endothermic reaction, equilibrium shifts in forward direction on heating.
In this reaction,
[Co(H2O6)]3+(Pink)(aq)+4Cl-(aq)[CoCl4]2-(Blue)(aq)+6H2O(l)
On cooling, the equilibriums shifts backward direction or on heating, the equilibrium shifts toward forward direction. Hence,
reaction is endothermic, i.e., H>0.