How many atoms are in a mole of calcium

How many moles are equivalent to 55.5g of nano3

Which statement about the stamps is correct?

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?