Which of the following statement is not correct?

Options

A. all alkalies are bases
B. all bases are not alkalies
C. all bases are alkalies
D. all water soluble hydroxides are alkalies

Answer

To determine which statement is not correct, we need to analyze each option provided in the question.

1. **Understanding Definitions**:
- **Base**: A substance that can accept hydrogen ions (H+) or donate a pair of valence electrons.
- **Alkali**: A specific type of base that is soluble in water and produces hydroxide ions (OH-) in solution.

2. **Analyzing Each Statement**:
- **Statement 1**: "All alkalis are bases."
- This statement is correct. Since alkalis are a subset of bases that are soluble in water, all alkalis are indeed bases.

- **Statement 2**: "All bases are alkalis."
- This statement is not correct. While all alkalis are bases, not all bases are alkalis because some bases are insoluble in water.

- **Statement 3**: "All bases are alkalis."
- This statement is also incorrect for the same reason as Statement 2.

- **Statement 4**: "All water-soluble hydroxides are alkalis."
- This statement is correct. Water-soluble hydroxides are classified as alkalis.

3. **Conclusion**:
- The statements that are not correct are "All bases are alkalis" and "All bases are alkalis." Since the question asks for the statement that is not correct, we can conclude that the second statement is the answer.

**Final Answer**: The statement that is not correct is "All bases are alkalis."