Which of the following order reperesent the order for the strength of base ?

Options

A. `CH_3CH_2^(-) gt NH_(2)^(-) gt HC -= C^(-) gt OH^(-)`
B. `H-C-=C^(-) gt CH_(3)CH_(2)^(-) gt NH_(2)^(-) gt OH^(-)`
C. `OH^(-) gt NH_(2)^(-) gt HC -= C^(-) gt CH_CH_(2)^(-)`
D. `NH_(2)^(-) gt HC -= C^(-) gt OH^(-) gt CH_CH_(2)^(-)`

Answer

To determine the order of strength of bases among the given compounds, we need to analyze the conjugate bases formed from the acids corresponding to each compound. The strength of a base is inversely related to the strength of its conjugate acid. Here’s a step-by-step solution:

### Step 1: Identify the Compounds
The compounds we need to analyze are:
1. H2O (water)
2. NH3 (ammonia)
3. HC≡CH (acetylene)
4. CH3 (methyl group)

### Step 2: Determine the Conjugate Acids
Each of these compounds can act as a base by accepting a proton (H+). The conjugate acids formed are:
1. H3O+ from H2O
2. NH4+ from NH3
3. H2C≡CH2 from HC≡CH
4. CH4 from CH3

### Step 3: Compare Acid Strengths
To determine the strength of the bases, we need to compare the strength of their conjugate acids:
- H3O+ (from H2O) is a strong acid.
- NH4+ (from NH3) is a weaker acid than H3O+.
- H2C≡CH2 (from HC≡CH) is a weaker acid than NH4+.
- CH4 (from CH3) is the weakest acid among these.

### Step 4: Infer Base Strengths
According to the Bronsted-Lowry theory:
- The stronger the acid, the weaker its conjugate base.
- Therefore, the order of base strength (from strongest to weakest) is the inverse of the order of acid strength:
1. CH3- (from CH3) - strongest base (weakest acid)
2. HC≡C- (from HC≡CH) - second strongest base
3. NH2- (from NH3) - weaker base
4. OH- (from H2O) - weakest base (strongest acid)

### Step 5: Final Order of Base Strength
Thus, the order of base strength from strongest to weakest is:
- CH3- > HC≡C- > NH2- > OH-

### Conclusion
The correct order representing the strength of bases is:
**CH3- > HC≡C- > NH2- > OH-**