The number of water molecules in $1 \ L$ of water is

What does $1 \text{ mole}$ of $CO_2$ contain?

How many $g$ of $H_2SO_4$ are present in $0.25 \, \text{mol}$ of $H_2SO_4$?

The number of moles of water present in a spherical water droplet of radius $1.0 \ cm$ is,(Given: Density of water in the droplet $= 1.0 \ g \ cm^{-3}$)

Which among the following elements has the highest number of atoms in $1 \ g$ each? (Atomic masses: $Au=197, Na=23, Cu=63.5, Fe=56$)

One atom of an element weighs $3.32 \times 10^{-23} \ g$. How many gram atoms are there in $20 \ kg$ of the element?