9 " mL of " a mixture of methane and ethylene was exploded with 30 mL (excess) of oxygen. After cooling, the volume was 21.0 mL. Further treatment with caustic potash solution reduced the volume to 7.0 mL. Determine the composition of the mixture.

Explanation

To determine the composition of the mixture of methane (CH₄) and ethylene (C₂H₄), we can follow these steps:

### Step 1: Define Variables
Let the volume of methane (CH₄) in the mixture be \( x \) mL. Therefore, the volume of ethylene (C₂H₄) will be \( 9 - x \) mL since the total volume of the mixture is 9 mL.

### Step 2: Write the Combustion Reactions
The combustion reactions for methane and ethylene are as follows:
1. For methane:
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