How many moles are in 1 x 10⁹ molecules of o2

Calculate the number of moles of ethane in 100 grams

What is the molar mass of a gas that has density of 2.054 g/l

For the reaction shown, find the limiting reactant for each of the following initial amounts of reactants. 4al(s)+3o2(g)→2al2o3(s) a) 1 molal, 1 mol o2 b) 4 molal, 2.6 mol o2 c) 16 molal, 13 mol o2 d) 7.4 molal, 6.5 mol o2