Under what soil condition do you think a farmer would treat the soil of his fields with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate) ?

You have two solutions, $A$ and $B$. The $pH$ of solution $A$ is $6$ and $pH$ of solution $B$ is $8$. Which solution has more hydrogen ion concentration Which of this is acidic and which one is basic?

What effect does the concentration of $H^+_{(aq)}$ ions have on the nature of the solution ?

Metal compound $A$ reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride.

A milkman adds a very small amount of baking soda to fresh milk.

$(a)$ Why does he shift the $pH$ of the fresh milk from $6$ to slightly alkaline ?

$(b)$ Why does this milk take a long time to set as curd ?

Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas ?