Is bismuth (bi) a compound or an element

Why does his teacher ask him to balance the equation by including the correct coefficient

Ascientist measures the speed of sound in a monatomic gas to be 449 m/s at 20∘c. what is the molar mass of this gas?

We are hoping to create 5.72 grams of glucose. the plant was given 4.75 liters of co2 and 2.81 g of h20. which reactant was the limiting reagent? how much excess mass did we have of the other reactant?