What is a closed container in relation to the law of conservation of mass

How many moles of carbon dioxide will form if 2.5 moles of c3h8 is burned

An excess of lithium oxide undergoes a synthesis reaction with water to produce lithium hydroxide li2o+h2o→2lioh if 1.05 g of water reacted, what is the theoretical yield of lithium hydroxide? a) 5.83 x 10–2 g lioh b) 1.17 x 10–1 g lioh c) 2.79 x 100 g lioh d) 1.40 x 100 g lioh

What is the mass of 2.00 l of an intravenous glucose solution with a density of 1.15 g/ml?