Answer is: pressure of oxygen is 31,3 kPa.
The total pressure<span> of an ideal gas mixture is the sum of the </span>partial pressures<span> of the gases in the mixture.
p(mixture) = p(helium) + p(oxygen) + p(carbon dioxide).
p(oxygen) = p(mixture) - (p(helium) + p(carbon dioxide)).
p(oxygen) = 101,4 kPa - (68,7 kPa + 1,4 kPa).
p(oxygen) = 101,4 kPa - 70,1 kPa.
p(oxygen) = 31,3 kPa.
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43 inHg = 43 inHg*2.54cm/in = 109.22cmHg * 10 mm/cm = 1092.2 mmHg
14.7 psi = 760 mmHg
1092.2mmHg * 14.7psi / 760 mmHg = 21.13 psi
Answer: option D. 21.13 psi
The answer you are looking for is A. If you need me to show you how I got the answer let me know. :)