Which of the following having having their radius ratio between`0.414` and `0.732`, i.e., for `NaCl` structure, have their radius ratio not in this range but posses `NaCl`-type structure?

Options

A. LiBr
B. KCl
C. RbCl
D. BaO

Explanation

To solve the question regarding the radius ratios of different compounds and their relation to the NaCl structure, we can follow these steps:

### Step 1: Understand the Radius Ratio Concept
The radius ratio is defined as the ratio of the radius of the cation (r+) to the radius of the anion (r-). For a compound to exhibit the NaCl structure, this ratio should fall between 0.414 and 0.732.

### Step 2: Identify the Given Compounds
The question provides several compounds for analysis:
1. KCl
2. BaO
3. RbCl
4. LiBr

### Step 3: Calculate or Recall the Radius Ratios
We need to find the radius ratios for each of the given compounds:
- **KCl**: The radius ratio (r+/r-) = 0.38
- **BaO**: The radius ratio (r+/r-) = 0.83
- **RbCl**: The radius ratio (r+/r-) = 0.77
- **LiBr**: The radius ratio (r+/r-) = 0.34

### Step 4: Compare with the NaCl Structure Range
Now, we compare each radius ratio with the range of 0.414 to 0.732:
- **KCl**: 0.38 (not in range)
- **BaO**: 0.83 (not in range)
- **RbCl**: 0.77 (not in range)
- **LiBr**: 0.34 (not in range)

### Step 5: Conclusion
From the above comparisons, we can conclude that all the given compounds (KCl, BaO, RbCl, and LiBr) have radius ratios that do not fall within the range of 0.414 to 0.732 but possess the NaCl-type structure.

### Final Answer
All the compounds listed (KCl, BaO, RbCl, and LiBr) have radius ratios outside the specified range but exhibit the NaCl-type structure.

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