`2E+N_(2)to2EN` (very hard substance)
`EN+H_(2)Oto` Acid + pungent smelling gas. Acid is:

Options

A. `HNO_(3)`
B. `H_(3)BO_(3)`
C. `HNO_(2)`
D. can be A & B

Explanation

To solve the question step by step, we will analyze the reactions and identify the substances involved.

### Step 1: Identify the Reaction
The first part of the reaction given is:
\[ 2E + N_2 \rightarrow 2EN \]
Here, \( E \) is an element that reacts with nitrogen (\( N_2 \)) to form a compound \( EN \).

**Hint:** Look for common compounds formed with nitrogen that are known to be hard substances.

### Step 2: Determine the Element \( E \)
From the context, \( E \) is likely boron (\( B \)). The compound formed, \( EN \), would then be boron nitride (\( BN \)).

**Hint:** Recall that boron nitride is a well-known hard material similar to diamond.

### Step 3: Hydrolysis of Boron Nitride
The next part of the question states:
\[ EN + H_2O \rightarrow \text{Acid} + \text{Pungent Smelling Gas} \]
This indicates that boron nitride undergoes hydrolysis when treated with water.

**Hint:** Hydrolysis typically involves the reaction of a compound with water to form an acid and other products.

### Step 4: Products of Hydrolysis
When boron nitride (\( BN \)) is hydrolyzed, it produces:
- Boric acid (\( H_3BO_3 \))
- Ammonia (\( NH_3 \)), which is the pungent smelling gas.

**Hint:** Consider the common products formed from the hydrolysis of boron compounds.

### Step 5: Identify the Acid
From the hydrolysis reaction, we have identified that the acid produced is boric acid (\( H_3BO_3 \)).

**Hint:** Check the options provided in the question to confirm which acid corresponds to the hydrolysis of boron nitride.

### Final Answer
The acid produced from the hydrolysis of boron nitride is:
**Boric acid (\( H_3BO_3 \))**

### Summary of Steps:
1. Identify the reaction and the compound formed (boron nitride).
2. Determine the element involved (boron).
3. Understand the hydrolysis process.
4. Identify the products of hydrolysis (boric acid and ammonia).
5. Conclude with the correct acid (boric acid).