Species having X-O-H linkage (X=non-metal with positive oxidation state) are called oxy acids and parent acid of a non-metal may exist in two form (a)-ic form of parent oxy acid (b)-us form parent oxy acid.
Q. Which of the following parent oxy acid does not have its pyro-oxy acid?

Options

A. `H_(2)SO_(3)`
B. `HNO_(3)`
C. `H_(3)PO_(3)`
D. `H_(4)SiO_(4)`

Answer

To solve the question regarding which parent oxy acid does not have its pyro-oxy acid, we will analyze each option step by step.

### Step 1: Understand Oxy Acids and Pyro-Oxy Acids
- Oxy acids are acids that contain oxygen, hydrogen, and another element (a non-metal) that is typically in a positive oxidation state. They have the general structure X-O-H.
- Pyro-oxy acids are formed when two units of a parent oxy acid lose a water molecule. This results in a new compound that has the structure X-O-X (where X is the non-metal).

### Step 2: Analyze Each Option
1. **H2SO3 (Sulfurous Acid)**:
- When two moles of H2SO3 lose water, they form H2O5 (Pyrosulfurous Acid). This means H2SO3 has a pyro-oxy acid.

2. **HNO3 (Nitric Acid)**:
- When two moles of HNO3 lose water, they form N2O5 (Dinitrogen Pentoxide). However, N2O5 does not have any hydrogen atoms bonded to oxygen, meaning it cannot release H+ ions, and thus it does not function as an acid. Therefore, HNO3 does not have a pyro-oxy acid.

3. **H3PO3 (Phosphorous Acid)**:
- When two moles of H3PO3 lose water, they form H4P2O5 (Pyrophosphorous Acid). This means H3PO3 has a pyro-oxy acid.

4. **H4SiO4 (Silicic Acid)**:
- When two moles of H4SiO4 lose water, they form H6Si2O7 (Pyrosilicic Acid). This means H4SiO4 has a pyro-oxy acid.

### Step 3: Conclusion
After analyzing all the options, we can conclude that the only parent oxy acid that does not have its pyro-oxy acid is **HNO3 (Nitric Acid)**.

### Final Answer:
**HNO3 (Nitric Acid)** does not have its pyro-oxy acid.