Carbon and oxygen react with each other in the ratio 3 : 8 by mass. What weight of carbon should be used to react completely with 40 g of oxygen?

Explanation

To solve the problem of how much carbon is needed to react completely with 40 grams of oxygen, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Mass Ratio**:
It is given that carbon and oxygen react in the ratio of 3:8 by mass. This means that for every 3 grams of carbon, 8 grams of oxygen are required.

2. **Set Up the Proportion**:
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