Give the decreasing order of `C-H` bond length in ethane, ethene and ethyne and why?

Explanation

To determine the decreasing order of C-H bond lengths in ethane, ethene, and ethyne, we can analyze the bond lengths and the hybridization states of carbon in these compounds.

### Step-by-Step Solution:

1. **Identify the Compounds and Their Bond Lengths:**
- Ethane (C2H6) has a C-H bond length of 111 picometers (1.11 Å).
- Ethene (C2H4) has a C-H bond length of 110.3 picometers (1.103 Å).
- Ethyne (C2H2) has a C-H bond length of 108 picometers (1.08 Å).
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