Compare the basic strength of the following compounds:
`underset((I))(C_(2)H_(5)O^(-))" "underset((II))(C_(2)H_(5)^(-))" "underset((III))(C_(2)H_(5)NH^(-))" "underset((IV))(NH_(2^(-)))" "underset((V))(F^(-))`

Answer

To compare the basic strength of the given compounds, we need to consider the concept of basicity in organic chemistry. Basic strength is influenced by the ability of a compound to donate a lone pair of electrons. The more electronegative an atom is, the less likely it is to donate its electrons, which inversely affects basic strength.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- (I) \( C_2H_5O^- \) (Ethoxide ion)
- (II) \( C_2H_5^- \) (Ethyl anion)
- (III) \( C_2H_5NH^- \) (Ethylamine anion)
- (IV) \( NH_2^- \) (Amide ion)
- (V) \( F^- \) (Fluoride ion)

2. **Understand Electronegativity**:
- Electronegativity is the tendency of an atom to attract electrons. The more electronegative an atom, the less likely it is to donate its electrons.
- The order of electronegativity for the relevant atoms is:
- \( F > O > N > C \)

3. **Analyze Each Compound**:
- **(I) Ethoxide ion \( C_2H_5O^- \)**: Oxygen is electronegative, which decreases its basicity compared to carbon-based anions.
- **(II) Ethyl anion \( C_2H_5^- \)**: Carbon is less electronegative than oxygen and nitrogen, making this a strong base.
- **(III) Ethylamine anion \( C_2H_5NH^- \)**: Nitrogen is less electronegative than oxygen, but more than carbon, so it has moderate basicity.
- **(IV) Amide ion \( NH_2^- \)**: Similar to ethylamine, but with no alkyl group to stabilize the negative charge, making it a weaker base than ethylamine.
- **(V) Fluoride ion \( F^- \)**: Fluorine is highly electronegative, making this the weakest base among the given compounds.

4. **Rank the Basic Strength**:
- Based on the above analysis, we can rank the basic strength from strongest to weakest:
1. \( C_2H_5^- \) (Ethyl anion) - Strongest
2. \( C_2H_5NH^- \) (Ethylamine anion)
3. \( NH_2^- \) (Amide ion)
4. \( C_2H_5O^- \) (Ethoxide ion)
5. \( F^- \) (Fluoride ion) - Weakest

### Final Order of Basic Strength:
\[ C_2H_5^- > C_2H_5NH^- > NH_2^- > C_2H_5O^- > F^- \]