Answer: a. The concentrations of the reactants and products have reached constant values
Explanation:
The reactions which do not go on completion and in which the reactant forms product and the products goes back to the reactants simultaneously are known as equilibrium reactions. For a chemical equilibrium reaction, equilibrium state is achieved when the rate of forward reaction becomes equal to rate of the backward reaction.
Equilibrium state is the state when reactants and products are present but the concentrations does not change with time and are constant.
Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios. It is expressed as 
K is the constant of a certain reaction when it is in equilibrium, while Q is the quotient of activities of products and reactants at any stage other than equilibrium of a reaction.
For a equilibrium reaction,

![K_{eq}=\frac{[B]}{[A]}](https://tex.z-dn.net/?f=K_%7Beq%7D%3D%5Cfrac%7B%5BB%5D%7D%7B%5BA%5D%7D)
Thus the correct answer is the concentrations of the reactants and products have reached constant values.
I don’t know if this is right but I thing It’s B
Answer:
NH3 has greater water solubility due to intermoleculate interactions
Explanation:
Hi:
If we represent the structures of NH3 and SbH3 we can see that they are similar to the naked eye, this is because N and Sb belong to the same group of the periodic table (group 15).
However, the electronegativity of N is greater than that of Sb. The NH3 molecule is polar and can form an intermolecular interaction called hydrogen bridge with water.
Sb is less electronegative than N. The SBH3 molecule forms an intermolecular interaction with water called dipole-induced dipole.
The zone with positive charge density of the water molecule (hydrogens) is oriented towards the zone with positive charge density of SBH3 (the pair of electrons not shared)
Stronger intermolecular junctions allow greater solubility of NH3 molecules.
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I think its chlorine Im not positive but im 99.9 precent shure