Which among the following is not a base?

In a basic aqueous solution,what happens to the basicity of the solution as the concentration of $[OH^-]$ increases?

Give three practical applications of neutralisation reaction.

What effect does an increase in the concentration of $H^{+}(aq)$ in a solution have on the $pH$ of the solution?

How do metal carbonates and metal hydrogen carbonates react with acids? Give their chemical equations. Name the gas evolved during the reaction. What will happen when this gas is passed through lime water?

Calcium phosphate is present in tooth enamel. Its nature is