Write true or false for the following statement:
The separation of $H^+$ ions from $HCl$ molecules can occur in the absence of water.

The metal salt $A$ is blue in colour. When salt $A$ is heated strongly over a burner,a substance $B$ present in it is eliminated and a white powder $C$ is left behind. When a few drops of a liquid $D$ are added to powder $C$,it becomes blue again.
$(a)$ Identify $A, B, C, D$.
$(b)$ Write the chemical equations involved.
$(c)$ Give an example of a salt which also shows the above property.

Write the chemical name and formula of the following:
$(a)$ Salt formed by the combination of a weak acid like carbonic acid and a strong base like sodium hydroxide.
$(b)$ Basic substance formed by the chlor-alkali process.
$(c)$ Substance added to cakes to make them fluffy.

What effect does an increase in the concentration of $H^{+}(aq)$ in a solution have on the $pH$ of the solution?

What is the chemical formula of gypsum?

If the concentration of hydronium ions in an aqueous solution is $[H_3O^+] = 1 \; M$,what is the $pH$ of the solution?