The decreasing basic order of the following is:
i. `F^(o-)`, ii. `Cl^(o-)`, iii. `Br^(o-)`, Iv. `I^(o-)`

Options

A. `(i) gt (ii) gt (iii) gt (iv)`
B. `(iv) gt (iii) gt (ii) gt (i)`
C. `(ii) gt (i) gt (iii) gt (iv)`
D. `(ii) gt (i) gt (iv) gt (iii)`

Explanation

To determine the decreasing basic order of the anions \( F^- \), \( Cl^- \), \( Br^- \), and \( I^- \), we follow these steps:

### Step 1: Understand the relationship between acids and their conjugate bases
The strength of an acid is inversely related to the strength of its conjugate base. This means that the stronger the acid, the weaker its conjugate base will be.

### Step 2: Identify the acids corresponding to the anions
The anions provided are the conjugate bases of the following acids:
- \( F^- \) is the conjugate base of HF
- \( Cl^- \) is the conjugate base of HCl
- \( Br^- \) is the conjugate base of HBr
- \( I^- \) is the conjugate base of HI

### Step 3: Determine the strength of the acids
The strength of these acids decreases in the following order:
- HI > HBr > HCl > HF

This means that HI is the strongest acid, while HF is the weakest.

### Step 4: Determine the basicity of the conjugate bases
Since stronger acids have weaker conjugate bases, we can deduce the basicity of the anions:
- \( I^- \) (from HI) is the weakest base
- \( Br^- \) (from HBr) is a stronger base than \( I^- \)
- \( Cl^- \) (from HCl) is a stronger base than \( Br^- \)
- \( F^- \) (from HF) is the strongest base

### Step 5: Write the decreasing order of basicity
Thus, the decreasing order of basicity for the anions is:
\[ F^- > Cl^- > Br^- > I^- \]

### Final Answer
The decreasing basic order of the given anions is:
\[ F^- > Cl^- > Br^- > I^- \]