Which salt solution has a $pH$ greater than $7$?

$(a)$ Study the following chemical equation:
$CaSO_4 \cdot 2H_2O \xrightarrow{373K} CaSO_4 \cdot \frac{1}{2}H_2O + \frac{3}{2}H_2O$
Name the reactant and the product. State one use of the product.

Which of the following phenomena occur when a small amount of acid is added to water?

In an attempt to demonstrate electrical conductivity through an electrolyte,the following apparatus was set up. Which among the following statement$(s)$ is(are) correct?
$(i)$ Bulb will not glow because electrolyte is not acidic.
$(ii)$ Bulb will glow because $NaOH$ is a strong base and furnishes ions for conduction.
$(iii)$ Bulb will not glow because circuit is incomplete.
$(iv)$ Bulb will not glow because it depends upon the type of electrolytic solution.
Solution: The apparatus shows a beaker containing a dilute $NaOH$ solution with two nails fixed on a rubber cork. $NaOH$ is a strong base that dissociates completely in water to provide $Na^+$ and $OH^-$ ions. These free ions act as charge carriers,allowing the electric current to flow through the solution and complete the circuit. Therefore,the bulb will glow. Statement $(ii)$ is correct.

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

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