Explain the reaction between metals and dilute hydrochloric acids with the help of an example. 

Write the balanced chemical equation of the reaction between calcium hydrogen carbonate and hydrochloric acid. 

When some pellets of sodium hydroxide are placed on red litmus paper then initially nothing happens but after some time the red litmus starts turning blue. Explain why. 

The aqueous solutions of glucose and starch do not show acidic properties but that of sulphuric acid and acetic acid do. Why? 

Are ${\mathrm{H}}^{+}$ ions present in basic solutions? If yes, then why is the solution basic? 

You have two solutions "$\mathrm{A}$" and "$\mathrm{B}$" in water. The pH value of solution "$\mathrm{A}$" is $6$ and that of "$\mathrm{B}$" is $8$. Which solution will have a higher concentration of hydrogen ions? Which one of the solutions is acidic and which is basic?