Question

An element X combines with the oxygen to form an oxide ${X_2}O$. This oxide is electrically conducting. Write the formula of the compound which is formed when X reacts with the chlorine.
(A) $XC{l_2}$
(B) $XCl$
(C) ${X_3}C{l_2}$
(D) None of the above.

Answer 1

We can find the compound that is formed when X reacts with Chlorine by finding the valency of X and Chlorine. We can find the valency of X from the oxide ${X_2}O$ that is formed by a combination of the element X and Oxygen.

Complete Solution :
Let us move to the problem given.
When an element X is combined with the oxygen, we will get an oxide which is ${X_2}O$. We know that the electrovalency of oxygen is -2. From this we can calculate the valency of X, which is +1.
We can write the equation as
$2{X^ + } + {O^{2 - }} \to {X_2}O$

Since the valency of X is +1, we can say that X belongs to Group IA, i.e. X is alkali metal.
Therefore, X can be Lithium, Sodium, Potassium, Caesium, Rubidium and Francium. The alkali metal X with valency +1 when combined with Chlorine with electrovalency -1, it will form the compound with formula $XCl$. The reaction is given below
${X^ + } + C{l^ - } \to XCl$
So, the correct answer is “Option B”. $XCl$.

Additional information:
Let us see the characteristics of alkali metals
- Alkali metal belongs to ‘s’ block element.
- Alkali metals have the general formula of $n{s^1}$.
- Alkali metals are highly reactive metals. Due to their high reactivity they are stored in kerosene or mineral oil.

Note: Alkali metals have various uses such as:
- Lithium is used in the manufacture of the lithium ion batteries.
- Sodium is used in the sodium vapour lamp. Sodium chloride is used as the table salt.
- Potassium is the main component in the NPK fertilisers.
- Francium is used in the spectroscopic experiments.