Answer:
you work out the moles by finding the grand formula mass them you divide the actual mass by the grand formula mass: 25/160 (my grand formula mass is probably slightly different from yours) which I got 0.15625 then I times it by 32(O2) and I got 5. but my periodic table is different. it's whole numbers. ;-)
Explanation:
4.44
Answer: V₂ = 37.71mL
Explanation: To determine the new volume of Helium gas, use the Combined Gas Law, which states the following relationship among pressure, volume and temperature:

where index 1 relates to the initial state of the gas and index 2 to the final state of the gas.
Temperature is in Kelvin, so:
T = °C + 273
For this situation, standard pressure is 1 atm. Temperatures will be:
T₁ = 20 + 273 = 293 K
T₂ = 91 + 273 = 364 K
Solving:



37.71
The new volume of He gas is 37.71 mL.