In a basic aqueous solution,how does the basicity of the solution change as the concentration of $[OH^{-}]$ ions decreases?

Crystals of copper sulphate are heated in a test tube for some time. What is the source of liquid droplets seen on the inner upper side of the test tube during the heating process?

To protect against tooth decay,we are advised to brush our teeth regularly. The nature of the toothpaste commonly used is:

Who proposed the acid-base theory of ionization?

If the $pH$ of the aqueous solutions $A, B, C$ and $D$ are $1.9, 2.5, 2.1$ and $3.0$ respectively,then what will be the order of acidity?

Give reasons for the following:
$(i)$ Why is it recommended that acid should be added to water and not water to acid?
$(ii)$ Why do compounds like alcohol and glucose not show acidic behavior even though they contain hydrogen?