How many moles are there in $4.9 \ g$ of $H_{2}SO_{4}$?

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

Equal volumes of hydrochloric acid and sodium hydroxide solutions of the same concentration are mixed. The $pH$ of the resulting solution is checked with a $pH$ paper. What would be the colour obtained? (You may use the colour guide given in the figure.)

Which of the following is a mineral acid?

Match the chemical substances given in Column $(A)$ with their appropriate application given in Column $(B)$.

Column $(A)$	Column $(B)$
$(A)$ Bleaching powder	$(i)$ Preparation of glass
$(B)$ Baking soda	$(ii)$ Production of $H_2$ and $Cl_2$
$(C)$ Washing soda	$(iii)$ Decolourisation
$(D)$ Sodium chloride	$(iv)$ Antacid

Write the chemical formula of bleaching powder. How is bleaching powder prepared? For what purpose is it used in drinking water?