What is the difference between the groups (vertical columns) and periods (horizontal rows) on the periodic table?

To calculate the molarity of a solution, you need to know the moles of solute and the

The size (radius) of an oxygen molecule is about 2.0 ×10−10m. make a rough estimate of the pressure at which the finite volume of the molecules should cause noticeable deviations from ideal-gas behavior at ordinary temperatures (t= 300k ). assume that deviatons would be noticeable when volume of the gas per molecule equals the volume of the molecule itself.

The molar mass of iron(fe) is 55.8 g/mol. what is the mass in grams of 2.25 moles of iron?