A diatomic gas belonging to group 15 combines with a halogen to form a trihalides which is fairly stable and inert. The trihalide is

Options

A. `NCl_(3)`
B. `PCl_(3)`
C. `BiF_(3)`
D. `NF_(3)`

Answer

To solve the question step by step, we will analyze the information provided and deduce the correct answer.

### Step 1: Identify the diatomic gas in Group 15
Group 15 of the periodic table includes the elements nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi). Among these, the only diatomic gas is nitrogen (N₂).

**Hint:** Look for diatomic gases in the periodic table and focus on Group 15.

### Step 2: Determine the halogen that combines with the diatomic gas
Halogens are found in Group 17 of the periodic table and include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The question states that the diatomic gas (N₂) combines with a halogen to form a trihalide.

**Hint:** Recall that halogens are known for forming compounds with other elements, particularly nonmetals.

### Step 3: Identify the possible trihalides formed by nitrogen
Nitrogen can form several halides, but we are interested in stable trihalides. The common trihalides of nitrogen are:
- Nitrogen trifluoride (NF₃)
- Nitrogen trichloride (NCl₃)

Among these, NF₃ is known to be fairly stable and inert under normal conditions.

**Hint:** Consider the stability of the compounds formed and focus on the common trihalides of nitrogen.

### Step 4: Conclusion
Based on the analysis, the stable and inert trihalide formed by the diatomic gas nitrogen (N₂) and a halogen (fluorine) is nitrogen trifluoride (NF₃).

**Final Answer:** The trihalide is nitrogen trifluoride (NF₃).

### Summary of Steps:
1. Identify the diatomic gas in Group 15 (N₂).
2. Determine the halogen that combines with nitrogen.
3. Identify the stable trihalides formed by nitrogen.
4. Conclude that the trihalide is nitrogen trifluoride (NF₃).