Answer:
2. X₂O
Step-by-step explanation:
- Elements in group 1A are known as alkali metal. Examples include lithium, sodium, and potassium among others.
- These elements have one valence electron in the outermost energy level and therefore form cations with a charge of +1.
- They have a valency of 2.
- Oxygen, on the other hand,has a valency of 2.
- Therefore, a chemical formula of a compound formed when an element in group 1A say X reacts with oxygen will be X₂O.
- To write the formula, we identify the symbol of the elements and their valence.
- Then the atoms of the two elements exchange their valencies which are written as a subscript on each symbol of an element.