A crystalline solid (A) reacts with hydrogen gas to form a monoatomic gas (B) and a highly associated liquid ( C).(A) is soluble in water and undergoes hydroloysis slowly to form (B),(C ) and a diatomic gas (D).When pure and dry (D) is subjected to a silent electric discharge an another pale blue gas (E) is produced which like (A) also acts a strong oxidising agent.(E) dissolves in potassium hydroxide forming an orange coloured solid which is paramagnetic in nature. (A) reacts with `IF_5, SbF_5, PF_5` etc to form the addition compounds. (C ) forms an addition compound (F) with KF with when electrolysed in molten state forms a most reactive gas (G).(B) and (G) (taken in 2:1) ratio when heated in nickel tube at `400^@ C` and 6 atm pressure forms (A).The first ionization energy `(IE_1)` of (B) is fairly close to (D).
Which of the following statements is true ?

Options

A. Gas (G) reacts with conc NaOH to form `OF_2`
B. Pale Blue gas (E) oxidises alkaline KI to `KIO_3`
C. Pale blue gas (E) in acidic medium reacts with `K_2Cr_2O_7` to form a bright blue coloured compound `(CrO_5)`
D. (B) and (C ) both

Explanation

To solve the given question step by step, we will analyze the information provided and deduce the identities of the compounds involved.

### Step 1: Identify Compound A
- **Given:** A crystalline solid (A) reacts with hydrogen gas to form a monoatomic gas (B) and a highly associated liquid (C).
- **Analysis:** Since (B) is a monoatomic gas, it is likely a noble gas. The only noble gas that can be formed from a reaction with a solid is Xenon (Xe). Therefore, we can assume that (A) is a compound of xenon, specifically \( \text{XeF}_2 \).

### Step 2: Identify Compounds B and C
- **Given:** (A) is soluble in water and undergoes hydrolysis slowly to form (B), (C), and a diatomic gas (D).
- **Analysis:** When \( \text{XeF}_2 \) is hydrolyzed, it produces \( \text{Xe} \) (B), \( \text{HF} \) (C), and \( \text{O}_2 \) (D). Thus, we have:
- (B) = \( \text{Xe} \)
- (C) = \( \text{HF} \)
- (D) = \( \text{O}_2 \)

### Step 3: Identify Compound E
- **Given:** When pure and dry (D) is subjected to a silent electric discharge, a pale blue gas (E) is produced, which acts as a strong oxidizing agent.
- **Analysis:** The pale blue gas produced from \( \text{O}_2 \) under silent electric discharge is ozone (\( \text{O}_3 \)). Thus, (E) = \( \text{O}_3 \).

### Step 4: Identify Compound F
- **Given:** (E) dissolves in potassium hydroxide forming an orange colored solid which is paramagnetic in nature.
- **Analysis:** The reaction of ozone with potassium hydroxide produces potassium ozonide (\( \text{KO}_3 \)), which is orange and paramagnetic. Thus, (F) = \( \text{KO}_3 \).

### Step 5: Identify Compound G
- **Given:** (C) forms an addition compound (F) with KF, and when electrolyzed in molten state forms a highly reactive gas (G).
- **Analysis:** The addition compound formed is \( \text{KHF}_2 \) (F), and upon electrolysis, it produces fluorine gas (\( \text{F}_2 \)), which is highly reactive. Thus, (G) = \( \text{F}_2 \).

### Step 6: Analyze the Reaction of B and G
- **Given:** (B) and (G) taken in a 2:1 ratio when heated in a nickel tube at \( 400^\circ C \) and 6 atm pressure forms (A).
- **Analysis:** The reaction of xenon (\( \text{Xe} \)) with fluorine (\( \text{F}_2 \)) in the specified conditions regenerates \( \text{XeF}_2 \) (A).

### Step 7: Compare Ionization Energies
- **Given:** The first ionization energy (IE1) of (B) is fairly close to (D).
- **Analysis:** The first ionization energy of xenon is indeed close to that of oxygen.

### Conclusion
Now we need to evaluate the statements provided in the question based on our findings:
1. **Statement A:** False - \( \text{F}_2 \) does not react with concentrated NaOH to form \( \text{OF}_2 \).
2. **Statement B:** True - Ozone (\( \text{O}_3 \)) can oxidize alkaline \( \text{KI} \) to \( \text{K}_2\text{O}_3 \).
3. **Statement C:** False - Ozone does not react with potassium dichromate to form \( \text{CrO}_5 \).

### Final Answer
The correct statement is **B**.