Answer : The correct option is, 13.7 mole
Solution : Given,
Moles of
= 27.4 moles
The given balanced chemical reaction is,

From the balanced chemical reaction, we conclude that
As, 2 moles of
react with 1 moles of 
So, 27.4 moles of
react with
moles of 
Therefore, the number of moles of oxygen
required are, 13.7 moles
Answer:

Explanation:
Hello,
In this case, since we can consider hydrogen gas as an ideal gas, we check the volume-pressure-temperature-mole relationship by using the ideal gas equation:

Whereas we are asked to compute the moles given the temperature in Kelvins, thr pressure in atm and volume in L as shown below:

Best regards.
The energy of the wave does not move through anything
Answer:
406.45mL
Explanation:
The following data were obtained from the question:
V1 = 350mL
P1 = 720mmHg
P2 = 630mmHg
V2 =?
The new volume can be obtain as follows:
P1V1 = P2V2
720 x 350 = 620 x v2
Divide both side by 620
V2 = (720 x 350) /620
V2 = 406.45mL
The new volume of the gas is 406.45mL