Which of the following oxides is most acidic and most basic respectively?
I(CaO), II`(K_2O)`, III`(H_2O)`, IV`(SO_3)`, V`(N_2O_5)`, VI`(SO_2)`.

Options

A. IV, II
B. V, I
C. VI, II
D. V, II

Answer

To determine which of the given oxides is the most acidic and the most basic, we can analyze the properties of each oxide based on the nature of the elements they are derived from.

### Step-by-Step Solution:

1. **Identify the Oxides**: The oxides given are:
- I. CaO (Calcium oxide)
- II. K₂O (Potassium oxide)
- III. H₂O (Water)
- IV. SO₃ (Sulfur trioxide)
- V. N₂O₅ (Dinitrogen pentoxide)
- VI. SO₂ (Sulfur dioxide)

2. **Classify the Oxides**:
- Basic Oxides: Generally formed by metals.
- Acidic Oxides: Generally formed by non-metals.

3. **Identify Basic Oxides**:
- From the list, CaO and K₂O are basic oxides since they are formed from metals (Calcium and Potassium).
- Among these, Potassium (K) is more metallic than Calcium (Ca), which means K₂O is more basic than CaO.

4. **Identify Acidic Oxides**:
- SO₃, N₂O₅, and SO₂ are acidic oxides since they are formed from non-metals (Sulfur and Nitrogen).
- To determine which is the most acidic, we consider the non-metallic character. Non-metallic character increases across a period and decreases down a group.
- Among SO₃, N₂O₅, and SO₂, N₂O₅ is the most acidic because nitrogen has a higher non-metallic character compared to sulfur.

5. **Conclusion**:
- The most basic oxide is K₂O.
- The most acidic oxide is N₂O₅.

### Final Answer:
- Most Basic: K₂O
- Most Acidic: N₂O₅