When a $pH$ paper is dipped in an aqueous solution,it turns blue. What is the approximate $pH$ value of that solution?

What type of substance is $NaOH$?

What is the unit of molar mass?

Which of the following is not a strong acid?

$A$ sulphate salt of a Group $2$ element of the Periodic Table is a white,soft substance,which can be moulded into different shapes by making its dough. When this compound is left in the open for some time,it becomes a hard solid mass and cannot be used for moulding purposes. Identify the sulphate salt and explain why it shows such behavior. Provide the chemical reaction involved.

Which of the following substances is an antacid?