Answer:
1. The oxidation number of Ca is 2, F is -1 in CaF₂
2. The oxidation number of H is 2, S is 6, O is -8 in H₂SO₄
3. The oxidation number of Ca is 2, S is 6, O is -8 in CaSO₄
4. The oxidation number of H is 1, F is -1 in HF
Explanation:
To get the oxidation number, we need to take the oxidation number of the whole compound 0. Then we need to know the oxidation number of the other elements and we need to take 'x' as the oxidation number of the unknown element.
Example:
In case of CaSO₄,
We can write an equation as-
CaSO₄ = 0
If we need to know the oxidation number of S
We can write the equation like this-
→2+ x+ (-2*4) = 0 (as we know the oxidation number of Ca is 2 as it has two electrons in its last shell which it gives to other elements to form bonds and the oxidation number of O is -2 as it takes 2 electrons to complete its outer shell)
→2+ x+ (-8) = 0
→2+ x- 8 = 0
→x- 6 = 0
→x = 6; which is the oxidation number of S
