Which of the following statement is incorrect ?

Options

A. `C_(2)H_(5)Br` reacts with alc. KOH to form `C_2H_4`
B. `C_2H_5Br` when treated with metallic sodium gives ethane
C. `C_2H_5Br` when treated with sodium ethoxide forms diethyl ether
D. `C_(2)H_(5)Br` with AgCN forms ethyl isocyanide

Answer

To determine which statement is incorrect regarding the reactions of ethyl bromide (C2H5Br), we will analyze each statement step by step.

### Step 1: Analyze the first statement
**Statement:** Ethyl bromide reacts with alcoholic KOH to form C2H4.

**Analysis:**
- Ethyl bromide (C2H5Br) reacts with alcoholic KOH, which acts as a strong base.
- The reaction mechanism is E2 (bimolecular elimination), where the base abstracts a proton from the beta carbon, and the bromine leaves as a leaving group.
- This results in the formation of ethylene (C2H4).

**Conclusion:** This statement is correct.

### Step 2: Analyze the second statement
**Statement:** C2H5Br when reacts with metallic sodium gives ethane.

**Analysis:**
- This reaction is known as the Wurtz reaction, where two alkyl halides react with sodium to form a higher alkane.
- For ethyl bromide (C2H5Br), the reaction with sodium would yield butane (C4H10), not ethane (C2H6).

**Conclusion:** This statement is incorrect.

### Step 3: Analyze the third statement
**Statement:** C2H5Br when treated with sodium ethoxide forms diethyl ether.

**Analysis:**
- Sodium ethoxide (C2H5O-Na+) acts as a nucleophile and can perform a nucleophilic substitution reaction with ethyl bromide.
- The reaction leads to the formation of diethyl ether (C2H5-O-C2H5) and sodium bromide (NaBr).

**Conclusion:** This statement is correct.

### Step 4: Analyze the fourth statement
**Statement:** C2H5Br with AgCN forms ethyl isocyanide.

**Analysis:**
- When ethyl bromide reacts with silver cyanide (AgCN), it leads to the formation of ethyl isocyanide (C2H5-NC).
- The reaction involves nucleophilic substitution where the cyanide ion attacks the carbon attached to bromine.

**Conclusion:** This statement is correct.

### Final Conclusion
After analyzing all the statements, the incorrect statement is:
**C2H5Br when reacts with metallic sodium gives ethane.**