$(i)$ Name the products formed when sodium hydrogen carbonate is heated.
$(ii)$ Write the chemical equation for the reaction involved in the above.

What happens when $CO_{2}$ is passed through lime water in excess?

Sodium carbonate is a basic salt because it is a salt of :

Acids do not show acidic behaviour in the absence of water but do so in water. Justify this statement with the help of a chemical equation.

What range of $pH$ is considered perfect for a fertile land?

Which of the following is(are) true when $HCl(g)$ is passed through water?
$(i)$ It does not ionise in the solution as it is a covalent compound.
$(ii)$ It ionises in the solution.
$(iii)$ It gives both hydrogen and hydroxyl ion in the solution.
$(iv)$ It forms hydronium ion in the solution due to the combination of hydrogen ion with water molecule.