Use the info to answer the question. $*$

$1$ point

An equilibrium that would favour the products is

a$.N{H}_4^{+}(aq)+H_{2}P{O}_4^{-}(aq)harrN{H}_3(aq)+H_{3}P{O}_4(aq)$

b$.HCN(aq)+H{S}^{-}(aq)harrC{N}^{-}(aq)+H_{2}S(aq)$

c$.HC{O}_3^{-}(aq)+P{O}_4^{3-}(aq)harrHP{O}_4^{2-}(aq)+C{O}_3^{2-}(aq)$

d$.HS{O}_4^{-}(aq)+HS{O}_3^{-}(aq)harr{H}_{2}S{O}_3(aq)+S{O}_4^{2-}(aq)$

A

B

C

D

$16.$ Solid citric acid was added to a flask containing water and then

$1$ point stoppered. Which of the following observations would indicate that an equilibrium had been established?

The forward and reverse reactions have stopped.

The pressure of the system is constant.

The mass of solid citric acid is completely dissolved.

The mass of solid citric acid remaining in the flask is constant.