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

Which of the following are present in a dilute aqueous solution of hydrochloric acid?

Which gas is released when acid reacts with metal?

What type of substance is $NaOH$?

What is the concentration of $[OH^-]$ in distilled water at $298 \; K$?

$R$. $K$. Patel,a chemistry teacher,explained the properties of inorganic acids in Std. $10$. He intentionally stated one of the properties incorrectly. Identify which one was wrong.