Indicate the `sigma and pi` bonds in the following molecules :
(i) `C_2 H_6`
(ii) `C_6 H_12`
(iii) `CH_2 Cl_2`
(iv) `CH_2 = C = CH_2`
(v) `CH_3 NO_2`
(vi) `HCON HCH_3`

Explanation

To indicate the sigma (σ) and pi (π) bonds in the given molecules, we will analyze each molecule step by step.

### (i) C₂H₆ (Ethane)
1. **Structure**: Ethane has a simple structure with two carbon atoms connected by a single bond, and each carbon is bonded to three hydrogen atoms.
2. **Bonds**:
- **Sigma Bonds**: Each C-H bond and the C-C bond are sigma bonds.
- Total: 6 C-H bonds + 1 C-C bond = 7 σ bonds.
- **Pi Bonds**: There are no double or triple bonds in ethane.
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