The precipitate will be the product that is insoluble in water, so your choices are  or .

Nitrate salts are always soluble in water, as are alkali metal salts such as sodium. Thus, we know that  will fully dissolve.

Halide salts (such as chlorides) are soluble in water, unless they are combined with silver, lead, or mercury. In this case, the silver atom makes the halide salt, , insoluble in water.  is the precipitate.

The precipitate will be the product that is insoluble in water, so your choices are  or .

Nitrate salts are always soluble in water, as are alkali metal salts such as sodium. Thus, we know that  will fully dissolve.

Halide salts (such as chlorides) are soluble in water, unless they are combined with silver, lead, or mercury. In this case, the silver atom makes the halide salt, , insoluble in water.  is the precipitate.

When writing the equilibrium expression for a reaction, remember that the products are on the top of the expression and the reactants are on the bottom. Any coefficients in the balanced reaction become the exponents in the equilibrium constant.

A general formula and corresponding equilibrium expression are given here:

Our equation follows the same format. Note, however, that pure solids and liquids are not included in the equilibrium expression, but pure gases (such as hydrogen) are. This is because the pressure of pure gases can affect equilibrium, but manipulating pure solids or liquids cannot.

When writing the equilibrium expression for a reaction, remember that the products are on the top of the expression and the reactants are on the bottom. Any coefficients in the balanced reaction become the exponents in the equilibrium constant.

A general formula and corresponding equilibrium expression are given here:

Our equation has only one product, but follows the same format.

Note that pure solids and liquids are not included in the equilibrium expression, but pure gases (such as nitrogen) are. This is because the pressure of pure gases can affect equilibrium, but manipulating pure solids or liquids cannot.

The general formula for the equilibrium constant of a reaction is:

For gaseous reactions, however, partial pressure can be substituted for concentration. For the given reaction, this means our equilibrium constant will be equal to the partial pressure of the products divided by the partial pressure of the reactants.

The equilibrium constant gives the ratio of product concentration to reactant concentration that results in equal forward and reverse rates of reaction. Essentially, the equilibrium constant defines the parameters of equilibrium for a given reaction. Altering the concentration of reactants or products will change the state of the reaction, driving it to produce more reactants or products in order to accommodate the change (Le Chatelier's principle), but will not alter the equilibrium parameters. Adding an enzyme will increase the rate of reaction by decreasing the activation energy, but will still not affect the equilibrium ratios.

The main factor that is capable of altering the equilibrium constant is change in temperature, which alters the amount of energy available to the system and affects the balance of equilibrium.

When creating the solubility product expression for a salt, keep in mind that salts are solids, and are therefore not included in the expression. Also, the coefficients in the balanced reaction become exponents in the expression.

For a general reaction, the solubility product constant would be given as follows:

Aluminum hydroxide will dissociate based on the following balanced reaction:

As a result, the solubility product expression is:

The correct answer gives the accurate definition of both the equilibrium constant and the reaction quotient. 

This is one of the properties of the law of mass action. The equilbrium constant for a reaction written in reverse is 1/K.

The only factor that changes the equilibrium constant is temperature. Changes in concentration of reactants or products by any means (whether addition, taking away solvent, or adding a chemical that will cause side reactions) will remove the system from equilibrium, but will not change the equilibrium constant.