What happens when a piece of $(i)$ Silver metal is added to copper sulphate solution? Also,write the balanced chemical equation if the reaction occurs.

Define a chemical equation. What is an unbalanced chemical equation called?

Observe the following diagram and answer the questions that follow:
$(i)$ Identify the gases evolved at anode and cathode.
$(ii)$ Why are the amounts of gases collected in the two test tubes not of the same volume?
$(iii)$ What type of reaction is this?
$(iv)$ Why should we use salt water?

$A$ substance $X$, which is an oxide of a group $2$ element, is used intensively in the cement industry. This element is present in bones also. On treatment with water, it forms a solution which turns red litmus blue. Identify $X$ and write the chemical reactions involved.

Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by liberation of heat. This process is called slaking of lime. Calcium hydroxide dissolves in water to form its solution called lime water. Which among the following is (are) true about slaking of lime and the solution formed?
$(i)$ It is an endothermic reaction
$(ii)$ It is an exothermic reaction
$(iii)$ The $pH$ of the resulting solution will be more than seven
$(iv)$ The $pH$ of the resulting solution will be less than seven

Write true or false for the following statement:
The insoluble substance formed during a chemical reaction is known as a precipitate.