Answer:
15 kPa.
Step-by-step explanation:
- The total pressure of a mixture of gases can be defined as the sum of the pressures of each individual gas:
Ptotal = P1 + P2 + … + Pn.
∴ Ptotal = P of oxygen + P of nitrogen + P of hydrogen.
∴ P of hydrogen = P total - (P of oxygen + P of nitrogen) = 85 kPa - (20 kPa + 50 kPa) = 15 kPa.