Ethane burns in oxygen to form `CO_2` and `H_2O` according to the equation :
`2C_2H_6 + 7O_2 rarr 4CO_2 + 6H_2O`
If 1250 cc of oxygen is burnt with 300 cc of ethane. Calculate :
the volume of unused `O_2`.

Explanation

To solve the problem of calculating the volume of unused oxygen when ethane burns in oxygen, we can follow these steps:

### Step 1: Write down the balanced chemical equation.
The combustion of ethane (C₂H₆) in oxygen (O₂) is represented by the equation:
\[ 2C_2H_6 + 7O_2 \rightarrow 4CO_2 + 6H_2O \]

### Step 2: Determine the volume ratio from the balanced equation.
From the balanced equation, we see that:
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