Equilibrium Tes...

The thermal dissociation equilibrium of $$CaC{O}_{3}\left(s\right)$$ is studied under different conditions.
             $$CaC{O}_{3}\left(s\right) \rightleftharpoons CaO\left(s\right) + C{O}_{2}\left(g\right)$$
For this equilibrium, the correct statement(s) is (are) :

Assertion: On mixing equal volumes of 1 M $$HCl$$ and of 2 M $$CH_3COONa$$, an acidic buffer solution is formed.
Reason: The resultant mixture contains $$CH_3COOH$$ and $$CH_3COONa$$ which are parts of acidic buffer.

The reaction which proceeds in the forward direction is:

The dissociation constant of $${NH}_{4}OH$$ can be given as

The equilibrium constant for the reaction, $${N}_{2}\left(g\right) + {O}_{2}\left(g\right) \rightleftharpoons 2NO\left(g\right)$$ is $$4\times {10}^{-4}$$ at $$2000  K$$. In presence of a catalyst, the equilibrium is attained $$10$$ times faster. Therefore, the equilibrium constant in the presence of the catalyst at $$2000 \:K$$ is:

Given a reaction:
$$C{l}_{2}\left(g\right) + 3{F}_{2}\left(g\right) \rightleftharpoons 2Cl{F}_{3}\left(g\right);    \Delta H = -329  kJ$$
Which of the following will increase the quantity of $$Cl{F}_{3}$$ in an equilibrium mixture of $$C{l}_{2}, {F}_{2}$$ and $$Cl{F}_{3}$$?

The volume of the reaction vessel containing an equilibrium mixture in the reaction,

Densities of diamond and graphite are $$3.5$$ and $$2.3  {g}/{mL}$$ respectively. Increase of pressure on the equilibrium:

Acetyl salicylic acid (aspirin) ionises in water as: $$HC_9H_7O_4+H_2O\rightarrow H_3O^+ + C_9H_7O_4^-;$$ $$(K_a = 2.75\times 10^{-9})$$. If two tablets of aspirin each of 0.32 g is dissolved in water to produce 250 mL solution, calculate $$[\overset{\circleddash}{O}H].$$ 

Calculate the equilibrium constants for the reactions with water of $$H_2PO_4^{\circleddash}, HPO_4^{2-}$$ and $$PO_4^{3-}$$ as base. Comparing the relative values of two equilibrium constants of $$H_2PO_4^{\circleddash}$$ with water, deduce whether solutions of this ion in water are acidic or bases. Deduce whether solutions of $$HPO_4^{2-}$$ are acidic or bases. Given $$K_1, K_2$$ and $$K_3$$ for $$H_3PO_4$$ are $$7.1\times 10^{-3}, 6.3\times 10^{-8}$$ and $$4.5\times 10^{-13}$$ respectively .