Equilibrium Tes...

Assertion: On addition of $$NH_4Cl$$ to $$NH_4OH, pH$$ decreases but remains greater than 7.
Reason: Addition of $$\overset{\circleddash}{N}H_4$$ ion decreases ionisation of $$NH_4$$, thus [OH] decreases and also pH decreases.

Assertion: On cooling in a freezing mixture, colour of the mixture turns to pink from deep blue for a reaction.
$$CO(H_2O)_6\,^{2+}(aq)+4Cl^{\circleddash}(aq)\rightleftharpoons  CoCl_4\,^{2-}(aq)+6H_2O(l)$$
                   (Pink)                                                    (Blue)
Reason: The reaction is endothermic in forward reaction, so on cooling the reaction, deep blue colour appears.

When $$NaN{O}_{3}$$ is heated in a closed vessel, oxygen is liberated and $$NaN{O}_{2}$$ is left behind. At equilibrium:

Assertion: $$pH$$ value of $$HCN$$ solution decreases when $$NaCN$$ is added to it
Reason: $$NaCN$$ provides a common ion $$CN^{\circleddash}$$ to $$HCN$$

The equilibrium constant K for the reaction:
$$2HI(g)\rightleftharpoons H_2(g)+I_1(g)$$ at room temp is 2.85 and that at 698 K is $$1.4\times 10^{-2}$$. This implies that the forward reaction is:

The equilibrium constant for a reaction,
$$A+B\rightleftharpoons C+D$$ is $$1.0\times 10^{-2}$$ at $$298$$ and is $$2.0$$ at $$373$$ K. The chemical process resulting in the formation of C and D is :

The system $$PCl_5(g)\rightleftharpoons PCl_3(g)+Cl_2(g)$$ attains equilibrium. If the equilibrium concentration of $$PCl_3(g)$$ is doubled, the concentration of $$Cl_2(g)$$ would become:

In the gaseous equilibrium $$A+2B\rightleftharpoons C+Heat$$, the forward reaction is favoured :

For a hypothetical reaction of the kind
$$AB_2(g)+\frac {1}{2}B_2(g)\rightleftharpoons AB_3(g);\Delta H=-x kJ$$ More $$AB_3$$ could be produced at equilibrium by :

The solubility of $$CO_2$$ in water increases with :