How many molecules are in 142.5 grams of CO2

Astudent carefully transfers 30 g of water and 30 g of alcohol in a glass tube, forming two layers and filling the tube completely. after sealing the tube, the student mixes the solutions, and notices a bubble that forms in the tube. what is the mass of the contents in the glass tube after mixing?

The molality of calcium chloride (cacl2) in an aqueous solution is 2.46 m. what is mole fraction of the solute?

What prefix multiplier is appropriate for reporting a measurement of 5.57 ×10−5 m?