In three moles of ethane (`C_(2)H_(6)`), calculate the following :
Number of moles of hydrogen atoms,

Answer

To solve the problem of finding the number of moles of hydrogen atoms in 3 moles of ethane (C₂H₆), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Composition of Ethane**:
Ethane (C₂H₆) consists of 2 carbon atoms and 6 hydrogen atoms.

2. **Determine the Number of Hydrogen Atoms in One Mole of Ethane**:
From the molecular formula, we can see that one mole of ethane contains 6 moles of hydrogen atoms.

3. **Calculate the Number of Moles of Hydrogen Atoms in 3 Moles of Ethane**:
To find the total number of moles of hydrogen atoms in 3 moles of ethane, we can use the unitary method:
\[ \text{Number of moles of hydrogen atoms} = \text{Number of moles of ethane} \times \text{Moles of hydrogen per mole of ethane} \]
\[ \text{Number of moles of hydrogen atoms} = 3 \text{ moles of C₂H₆} \times 6 \text{ moles of H} \]
\[ \text{Number of moles of hydrogen atoms} = 18 \text{ moles of H} \]

4. **Conclusion**:
Therefore, in 3 moles of ethane, there are 18 moles of hydrogen atoms.

### Final Answer:
The number of moles of hydrogen atoms in 3 moles of ethane (C₂H₆) is **18 moles**.