What is the approximate $pH$ value for a solution,if $pH$ paper turns pink when dipped into it?

Dry hydrogen chloride gas does not turn blue litmus red whereas hydrochloric acid does. Give one reason.

Give reasons for the following:
$(a)$ Dry $HCl$ gas does not change the colour of dry litmus paper.

What is the $pH$ value of a basic aqueous solution?

$A$ 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.

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