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

$(a)$ $A$ salt is produced by the reaction between an acid and a base. Identify the acid and the base from which the following salts have been formed:
$(i)$ $Na_{2}SO_{4}$
$(ii)$ $NH_{4}Cl$
$(iii)$ $KNO_{3}$
$(iv)$ $NaCl$

For making cake,baking powder is used. If at home your mother uses baking soda instead of baking powder in the cake,
$(a)$ how will it affect the taste of the cake and why?
$(b)$ how can baking soda be converted into baking powder?
$(c)$ what is the role of tartaric acid added to baking soda?

Identify the compound $X$ on the basis of the reactions given below. Also,write the name and chemical formulae of $A$,$B$ and $C$.

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

Write true or false for the following statement:
The process of dissolving an acid or a base in water is a highly exothermic process.