Basic strength order of halide is :-

Options

A. ` Cl^(-)lt Br^(–)lt I^(–)lt F^–`
B. `F^– lt I^– lt Br^– lt Cl^–`
C. ` I^– lt Br^– lt Cl^– lt F^–`
D. ` Cl^– lt F^– lt I^– lt Br^–`

Answer

To determine the basic strength order of halides (fluoride, chloride, bromide, and iodide), we need to analyze the factors that influence their basicity. Here’s a step-by-step solution:

### Step 1: Identify the Halides
The halides we are considering are:
- Fluoride (F^-)
- Chloride (Cl^-)
- Bromide (Br^-)
- Iodide (I^-)

### Step 2: Understand Basicity
Basicity refers to the ability of a species to accept protons (H^+ ions). In the case of halides, the larger the halide ion, the more stable it is as a base because it can better accommodate the negative charge.

### Step 3: Analyze Size and Bond Strength
As we move down the group in the periodic table from fluorine to iodine:
- The size of the halide ions increases (F^- < Cl^- < Br^- < I^-).
- The bond dissociation enthalpy decreases, meaning that it becomes easier to break the bond to release H^+ ions.

### Step 4: Consider Electronegativity
Fluorine is the most electronegative element, which makes F^- a very stable ion. However, this high electronegativity also means that fluoride is less willing to donate its electron pair to bond with H^+, making it less basic compared to the other halides.

### Step 5: Determine the Order of Basicity
Based on the size and bond strength:
- Iodide (I^-) is the least basic because it is the largest and can easily donate H^+.
- Bromide (Br^-) is more basic than iodide but less than chloride.
- Chloride (Cl^-) is more basic than bromide.
- Fluoride (F^-) is the most basic due to its ability to stabilize the negative charge despite its high electronegativity.

### Conclusion: Basic Strength Order
Thus, the order of basic strength of halides is:
**I^- < Br^- < Cl^- < F^-**

### Final Answer
The correct option is C: Iodide < Bromide < Chloride < Fluoride.

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