The correct answer is option 3, which is 3.
Valency refers to the number of electrons an atom can gain, lose, or share in order to achieve a stable electron configuration. In the compound Ga2O3, gallium (Ga) is combined with oxygen (O) to form a compound. The formula Ga2O3 indicates that there are two gallium atoms and three oxygen atoms in the compound.
To determine the valency of gallium, we can look at the ratio of gallium to oxygen in the compound. Each gallium atom is bonded with three oxygen atoms. This suggests that gallium has a valency of 3, as it needs to lose three electrons to achieve a stable electron configuration.
To summarize, the valency of gallium in the compound Ga2O3 is 3, as it forms three bonds with oxygen atoms.