<u>Answer:</u> The concentration of unknown phosphoric acid solution is 0.034 M
<u>Explanation:</u>
To calculate the concentration of acid, we use the equation given by neutralization reaction:

where,
are the n-factor, molarity and volume of acid which is 
are the n-factor, molarity and volume of base which is NaOH.
We are given:

Putting values in above equation, we get:

Hence, the concentration of unknown phosphoric acid solution is 0.034 M
Answer:
See explanation
Explanation:
From the information provided;
P1 = initial pressure = 758.0 mmHg
T1 = Initial temperature = 32.7°C + 273 = 305.7 K
V1 = Initial volume?
P2 = Final pressure = 364.2 mmHg
V2 = Final volume = 425 L
T2= Final Temperature = 3.10°C + 273 = 276.1 K
P1V1/T1 = P2V2/T2
P1V1T2 =P2V2T1
V1 = P2V2T1/P1T2
V1 = 364.2 * 425 * 305.7/758.0 * 276.1
V1 = 226. 18 L
B) Total pressure = 100.0 kPa
Pressure of Helium = 83.1 kPa
Pressure of carbon dioxide = 0.1000 kPa
Pressure of oxygen ?
From Dalton's law of partial pressures;
PT = P1 + P2 +P3 +.........
Hence;
Poxygen = 100.0 kPa - (83.1 kPa + 0.1000 kPa)
Poxygen = 16.8 kPa