ANS:D - 20%

To solve this problem, we need to find the initial mole percent of H2 and then determine how it changes when 50% of the H2O condenses.

1. Initial Mole Percent of H2: The initial mole percent of H2 can be found from the given molar composition of the gas, which is 10% H2.
2. Change in Mole Percent of H2 after Condensation: When 50% of the H2O condenses, the amount of H2O in the gas decreases, but the amount of H2 remains the same. So, we only need to consider the change in the amount of H2O.

Initially, H2O constitutes the balance of the gas, which is 100% - (10% + 10% + 30%) = 50%. When 50% of H2O condenses, the remaining amount of H2O is reduced by 50% * 50% = 25%. Now, we'll calculate the final mole percent of H2 in the gas on a dry basis: Initial mole percent of H2 = 10% Remaining mole percent of H2O after condensation = 50% - 25% = 25% Total mole percent of dry gas = 100% - 25% = 75% Mole percent of H2 in the dry gas = (Initial mole percent of H2 / Total mole percent of dry gas) * 100 Mole percent of H2=(10%75%)×100=215×100=13.33%Mole percent of H2​=(75%10%​)×100=152​×100=13.33% So, the final mole percent of H2 in the gas on a dry basis will be approximately 13.33%. None of the provided options match this value. Did I make an error in my calculations, or would you like me to revisit the problem?