A brown coloured mixture of two gases is obtained by the reduction of 6N nitric acid with metallic copper. Condeness to a blue liquid which on freezing at `-30^(@)C` gives a blue solid. The correct choice for blue liquid or solid is .

Options

A. It is referred to as the anhydride of nitrous acid
B. It is an acidic oxide and hence dissolves in alaklies producing nitries.
C. It can also be prepared by the action of `50% HNO_(3)` on arsenious oxide and then cooling to 250 K.
D. All of these

Answer

To solve the question step by step, we need to analyze the information given and the reactions involved:

### Step 1: Identify the Reaction
The question states that a brown-colored mixture of gases is obtained by the reduction of 6N nitric acid (HNO3) with metallic copper (Cu). The relevant reaction can be summarized as follows:

\[ \text{Cu} + 4 \text{HNO}_3 \rightarrow \text{Cu(NO}_3)_2 + 2 \text{NO} + 2 \text{H}_2\text{O} \]

In this reaction, copper reacts with nitric acid to produce copper nitrate, nitrogen monoxide (NO), and water. The nitrogen monoxide can further react with oxygen to form nitrogen dioxide (NO2), contributing to the brown color of the gas mixture.

### Step 2: Analyze the Gases Produced
The brown-colored mixture consists of nitrogen monoxide (NO) and nitrogen dioxide (NO2). Both of these gases can condense into a blue liquid when cooled.

### Step 3: Condensation to Blue Liquid
Upon cooling, the brown gas mixture condenses into a blue liquid. This blue liquid is likely to be dinitrogen tetroxide (N2O4), which exists in equilibrium with nitrogen dioxide (NO2). The equilibrium can be represented as:

\[ 2 \text{NO}_2 \rightleftharpoons \text{N}_2\text{O}_4 \]

### Step 4: Freezing Point of the Blue Liquid
The question states that this blue liquid freezes at -30°C to give a blue solid. The blue solid formed upon freezing is likely to be dinitrogen tetroxide (N2O4), which has a freezing point around -11.2°C. However, the question indicates a blue solid at -30°C, which suggests that the solid might be a different nitrogen oxide, possibly nitrous oxide (N2O3), which can appear blue in color.

### Step 5: Conclusion
Based on the analysis, the blue liquid is likely to be dinitrogen tetroxide (N2O4), and the blue solid formed upon freezing is likely to be dinitrogen trioxide (N2O3).

### Final Answer:
- The blue liquid is **dinitrogen tetroxide (N2O4)**.
- The blue solid is **dinitrogen trioxide (N2O3)**.