Chemistry

Question Analysis
This question tests the student's ability to use Dalton's Law of Partial Pressures to find the partial pressure of an unknown gas in a mixture when the total pressure and the partial pressures of other gases are known.

Key Concept Explanation
Dalton's Law of Partial Pressures states that the total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture.

Step-by-step Solution
1. Identify the total pressure of the gas mixture: 900 kPa.
2. Identify the partial pressures of the known gases: 400 kPa for argon and 300 kPa for carbon dioxide.
3. Subtract the sum of the known partial pressures from the total pressure: