What will be the value of $pH$ if blue litmus paper turns red in an aqueous solution?

You have two solutions,$A$ and $B$. The $pH$ of solution $A$ is $6$ and the $pH$ of solution $B$ is $8$. Which solution has a higher hydrogen ion concentration? Which of these is acidic and which one is basic?

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?

Write true or false for the following statement:
Higher is the hydronium ion concentration,higher is the $pH$ value.

In a basic aqueous solution,if the concentration of $[OH^-]$ decreases,what happens to the $pOH$?

How is an aqueous solution with $pH$ $12$ compared to an aqueous solution with $pH$ $9$?