For compounds ,
A : Tetracynoethene
B : Carbon dioxide
C: Benzene
D : 1 , 3-Butaidene .
Ratio of `sigma` and ` pi` bonds is in order :

Options

A. `A=BltCltD`
B. `A=BltDltC`
C. `A=B=C=D`
D. `CltCltAltB`

Answer

To determine the ratio of sigma (σ) and pi (π) bonds in the given compounds, we will analyze each compound step by step.

### Step 1: Analyze Tetracyanoethene (Compound A)
1. **Structure**: Tetracyanoethene has the formula C2(CN)4. It can be visualized as ethene (C=C) with four cyano (–C≡N) groups attached.
2. **Bonds**:
- The double bond between the two carbon atoms contributes 1 σ bond and 1 π bond.
- Each cyano group (–C≡N) contributes 1 σ bond and 2 π bonds.
- Total from 4 cyano groups: 4 σ bonds and 8 π bonds.
3. **Total Count**:
- Total σ bonds = 1 (from C=C) + 4 (from cyano groups) = 5 σ bonds.
- Total π bonds = 1 (from C=C) + 8 (from cyano groups) = 9 π bonds.
4. **Ratio**:
- Ratio of σ to π = 5:9.

### Step 2: Analyze Carbon Dioxide (Compound B)
1. **Structure**: Carbon dioxide (CO2) has a linear structure: O=C=O.
2. **Bonds**:
- The double bond between carbon and each oxygen contributes 1 σ bond and 1 π bond.
3. **Total Count**:
- Total σ bonds = 1 (from C=O) + 1 (from C=O) = 2 σ bonds.
- Total π bonds = 1 (from C=O) + 1 (from C=O) = 2 π bonds.
4. **Ratio**:
- Ratio of σ to π = 2:2 = 1:1.

### Step 3: Analyze Benzene (Compound C)
1. **Structure**: Benzene (C6H6) has a hexagonal structure with alternating double bonds.
2. **Bonds**:
- Each C-H bond contributes 1 σ bond.
- Each C=C bond contributes 1 σ bond and 1 π bond.
3. **Total Count**:
- Total σ bonds = 6 (C-H) + 3 (C=C) = 9 σ bonds.
- Total π bonds = 3 (from C=C).
4. **Ratio**:
- Ratio of σ to π = 9:3 = 3:1.

### Step 4: Analyze 1,3-Butadiene (Compound D)
1. **Structure**: 1,3-Butadiene (C4H6) has the structure H2C=CH-CH=CH2.
2. **Bonds**:
- Each double bond contributes 1 σ bond and 1 π bond.
3. **Total Count**:
- Total σ bonds = 3 (C-C) + 4 (C-H) = 7 σ bonds.
- Total π bonds = 2 (from two C=C).
4. **Ratio**:
- Ratio of σ to π = 7:2.

### Summary of Ratios
- Compound A (Tetracyanoethene): 5:9
- Compound B (Carbon Dioxide): 1:1
- Compound C (Benzene): 3:1
- Compound D (1,3-Butadiene): 7:2

### Final Ratios in Order
The ratios of σ to π bonds in order are:
1. Carbon Dioxide: 1:1
2. Benzene: 3:1
3. 1,3-Butadiene: 7:2
4. Tetracyanoethene: 5:9

### Final Answer
The order of the ratios of σ to π bonds for the compounds is:
1. Carbon Dioxide (1:1)
2. Benzene (3:1)
3. 1,3-Butadiene (7:2)
4. Tetracyanoethene (5:9)

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