In the laboratory, chloroform is prepared by which of the following method?

Options

A. By oxidation of isopropyl alcohol with bleaching powder
B. By reduction of carbon tetrachloride with Fe+`H_(2)`O
C. By oxidation of carbon tertrachloride with bleaching powder
D. None of the above

Answer

To determine the laboratory method for preparing chloroform, let’s analyze the options provided step by step.

### Step 1: Analyze Option 1
**Option 1: By oxidation of isopropyl alcohol with bleaching powder.**
- Chloroform can indeed be produced from isopropyl alcohol (propan-2-ol) using bleaching powder (calcium oxychloride, Ca(OCl)2).
- The reaction involves the oxidation of isopropyl alcohol by chlorine gas, which is generated from the bleaching powder in the presence of water.
- The reaction proceeds as follows:
1. **Formation of Chlorine**: Ca(OCl)2 reacts with water to produce Cl2 and calcium hydroxide.
2. **Oxidation of Isopropyl Alcohol**: Isopropyl alcohol reacts with Cl2 and nascent oxygen to form propanone (acetone) and HCl.
3. **Further Reaction**: The propanone can then react with chlorine and calcium hydroxide to yield chloroform (CHCl3) and calcium acetate.

Thus, this option is a valid laboratory method for preparing chloroform.

### Step 2: Analyze Option 2
**Option 2: By reduction of carbon tetrachloride with iron and water.**
- This method involves the partial reduction of carbon tetrachloride (CCl4) to produce chloroform.
- The reaction is as follows:
- CCl4 + nascent hydrogen (from iron and water) → CHCl3 + HCl.
- While this reaction does produce chloroform, it is not typically performed in a laboratory setting for the preparation of chloroform. Therefore, this option is not considered a laboratory method.

### Step 3: Analyze Option 3
**Option 3: By oxidation of carbon tetrachloride with bleaching powder.**
- This method is not a standard laboratory method for producing chloroform.
- Oxidation of carbon tetrachloride does not lead to chloroform and is not a recognized laboratory preparation method.

### Step 4: Analyze Option 4
**Option 4: None of the above.**
- Since we have established that Option 1 is a valid method for preparing chloroform, this option is incorrect.

### Conclusion
After analyzing all the options, we can conclude that the correct answer is:
**Chloroform is prepared in the laboratory by oxidation of isopropyl alcohol with bleaching powder.**