`Et-N^(o+)-=C^(ɵ) underset(or HgO or O_(3))overset(Cl_(2)+DMSO)(rarr)`. The compound `(A)` is:

Options

A. a.Ethyl methyl amine
B. b.Ethylnitrile
C. c.Ethyl isocyanate
D. d.Ethyl cyanate

Explanation

To solve the question regarding the reaction of ethyl isocyanide with various reagents, we will analyze the reactions step by step.

### Step 1: Identify the Reactant
The reactant given is ethyl isocyanide, which can be represented as:
\[ \text{C}_2\text{H}_5\text{N}^{\oplus} \equiv \text{C}^{\ominus} \]
This structure indicates that ethyl isocyanide has a positive charge on nitrogen and a negative charge on carbon.

### Step 2: Determine the Reagents
The reagents mentioned in the question are:
1. Chlorine (Cl₂) and Dimethyl Sulfoxide (DMSO)
2. Mercuric Oxide (HgO)
3. Ozone (O₃)

### Step 3: Analyze the Reaction with Chlorine and DMSO
When ethyl isocyanide reacts with chlorine in the presence of DMSO, which is an oxidizing agent, it oxidizes the isocyanide to isocyanate. The reaction can be represented as follows:
\[ \text{C}_2\text{H}_5\text{N} \equiv \text{C} + \text{Cl}_2 + \text{DMSO} \rightarrow \text{C}_2\text{H}_5\text{N} = \text{C} = \text{O} + \text{Cl}_2 \]
The product formed is ethyl isocyanate:
\[ \text{C}_2\text{H}_5\text{N} = \text{C} = \text{O} \]

### Step 4: Analyze the Reaction with Mercuric Oxide
When ethyl isocyanide reacts with mercuric oxide (HgO), it also leads to the formation of ethyl isocyanate. The reaction can be represented as:
\[ \text{C}_2\text{H}_5\text{N} \equiv \text{C} + \text{HgO} \rightarrow \text{C}_2\text{H}_5\text{N} = \text{C} = \text{O} + \text{Hg}_2\text{O} \]
Here, mercuric oxide is reduced to mercurous oxide (Hg₂O).

### Step 5: Analyze the Reaction with Ozone
When ethyl isocyanide reacts with ozone (O₃), it similarly produces ethyl isocyanate:
\[ \text{C}_2\text{H}_5\text{N} \equiv \text{C} + \text{O}_3 \rightarrow \text{C}_2\text{H}_5\text{N} = \text{C} = \text{O} + \text{O}_2 \]
In this case, ozone is reduced to oxygen gas.

### Conclusion
In all three cases (with Cl₂ + DMSO, HgO, and O₃), the product formed is ethyl isocyanate (C₂H₅N=C=O). Therefore, the compound (A) is:
\[ \text{Ethyl Isocyanate} \]

### Final Answer
The compound (A) is **ethyl isocyanate**.

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