Answer is b. Hope it help
Mass number is the number of protons and neutrons in an atom, and it tells us about the mass of the atom in amu, or atomic mass units. Atomic mass is the average mass of all the isotopes of a certain type. It is a weighted average that takes into account the abundances of all of the different isotopes
hope this helps :)
The answer is temperature (may be wrong)
1) We apply the ideal gas equation:
PV = nRT
n = (21300 x 3/1000) / (8.314 x 323)
n = 0.024
Your answer is correct.
2) Total pressure = Partial pressure of Hydrogen + Partial pressure of water
134.7 = 122.4 + Pw
Pw = 12.3 kPa
Your answer is correct
3) The molar fraction, volume fraction and pressure fraction of gasses are the same thing.
Thus, percentage pressure of Oxygen = 10%
Pressure of Oxygen = 2.04 x 10⁴ x 0.1
= 2.04 x 10³ kPa
Your answer is correct
Well done!