One method of removing excess CO₂ (g) from the crew compartment of spacecraft and submarines is to react it with LiOH (s) according to the following equation CO₂(g) + 2 LiOH (s) yields Li₂CO₃ (s) + H₂O(l). How many liters of CO₂ (g) at 27.0 °C and 750 torr could be removed by 1000 g of LiOH(s) ?

How many mols is 1000 grams of LiOH ?

1 mol = 7 + 16 + 1 = 24 grams / 1 mol
1000 grams * (1 mol/24 grams) = 41.7 mols LiOH
so
20.8 mols of CO2
now use PV = n R T to get V

1,000 g LiOH. I calculated 23.94 g/mol for LiOH. You should confirm that.

CO₂(g) + 2 LiOH (s) yields Li₂CO₃ (s) + H₂O(l).
moles LiOH = grams/molar mass = 1,000/23.94 41.77 moles.
Convert to mols CO2 using the coefficients in the balanced equation like this.
41.77 moles LiOH x (1 mols CO2/2 moles LiOH) = 41.77/2 = 20.88 moles CO2.
Then convert to liters CO2 at the conditions listed using PV = nRT. Remember to convert T to kelvin from Celsius.
Post your work if you get stuck.