Which of the following methods is (are) used to prepare colloidal sols?

Options

A. Hydrolysis
B. Double decomposition
C. Oxidation and reduction
D. All of these

Answer

To determine which methods are used to prepare colloidal sols, we can analyze each method mentioned in the question:

1. **Hydrolysis**: This method involves the reaction of a substance with water. It is commonly used to prepare colloidal hydroxides. For example, when metal salts react with water, they can form metal hydroxide colloids. Therefore, hydrolysis is a valid method for preparing colloidal sols.

2. **Double Decomposition**: This method involves the reaction between two compounds to form new compounds, one of which is often a precipitate. Colloidal sols can be prepared through double decomposition reactions. An example is the formation of arsenic trisulfide (As2S3) from the reaction of arsenic and sulfide ions. Hence, double decomposition is also a valid method for preparing colloidal sols.

3. **Oxidation**: This method is used to prepare colloidal sols of non-metals. For example, the oxidation of certain non-metallic compounds can lead to the formation of colloidal particles. Therefore, oxidation is another method used to prepare colloidal sols.

4. **Reduction**: This method is primarily used to prepare colloidal sols of metals. For example, reducing metal ions in solution can lead to the formation of colloidal metal particles. Thus, reduction is also a valid method for preparing colloidal sols.

In conclusion, all the methods listed (hydrolysis, double decomposition, oxidation, and reduction) are used to prepare colloidal sols.

**Final Answer**: All of the methods mentioned (hydrolysis, double decomposition, oxidation, and reduction) are used to prepare colloidal sols.

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