Sulphur on reaction with concentrated `HNO_3`. Gives `(A)` which reacts with reacts with `NaOH` gives `(B).(A)` and `(B)` are

Options

A. `H_2 SO_3, Na_2 S_2 O_3`
B. `NO_2, Na_2 S`
C. `H_2 SO_4, Na_2 SO_4`
D. `H_2 S_2 O_3, Na_2 S_2 O_3`

Explanation

To solve the question, we need to analyze the reaction of sulfur with concentrated nitric acid (HNO3) and the subsequent reaction with sodium hydroxide (NaOH).

### Step-by-step Solution:

1. **Identify the Reaction of Sulfur with Concentrated HNO3**:
- When sulfur (S) reacts with concentrated nitric acid (HNO3), it is oxidized. The main product of this reaction is sulfuric acid (H2SO4) and nitrogen dioxide (NO2) is also produced as a byproduct.
- The balanced chemical equation for this reaction is:
\[ S + 6HNO_3 \rightarrow H_2SO_4 + 6NO_2 + 2H_2O \]
- Here, the product (A) is **H2SO4** (sulfuric acid).

2. **Reaction of H2SO4 with NaOH**:
- The next step is to consider the reaction of sulfuric acid (H2SO4) with sodium hydroxide (NaOH). This is a typical acid-base neutralization reaction.
- The balanced equation for this reaction is:
\[ H_2SO_4 + 2NaOH \rightarrow Na_2SO_4 + 2H_2O \]
- In this reaction, sodium sulfate (Na2SO4) is formed as the product (B).

3. **Final Products**:
- From the above reactions, we conclude that:
- Product (A) is **H2SO4** (sulfuric acid).
- Product (B) is **Na2SO4** (sodium sulfate).

### Conclusion:
Thus, the answer to the question is:
- (A) = H2SO4
- (B) = Na2SO4