An element M burns in oxygen to form an ionic compound MO. Write the formula of the compounds formed if this element is made to combine with chlorine and sulphur separately.

 Question:

An element M burns in oxygen to form an ionic compound MO. Write the formula of the compounds formed if this element is made to combine with chlorine and sulphur separately.

Solution:

MCl₂ and MS

Explanation:

Valency of Oxygen is 2. Since formula of oxide is MO, valency of M must be 2 so that both the two get cancelled and the formula becomes MO.

So, valency of M is 2.

Now, valency of chlorine is 1

By criss-cross method,

M    Cl

2       1

1 goes to M and 2 goes to Cl

So, the formula is MCl₂.

Similarly, valency of sulphur is 2.

By criss-cross method,

M   S

2     2

Both the two get cancelled, and so the formula is MS.