Calculate the number of moles of cl atoms in 1.81×1024 formula units of magnesium chloride, mgcl2.

To convert from formula units to moles, you need to divide by Avogardo's constant. And then remember that there will be 2 moles of Cl for every 1 mole of MgCl₂.

1.81*10^24 formula units MgCl₂ * (1 mole MgCl₂/6.022*10^23 formula units MgCl₂) * (2 moles Cl/1 mole MgCl₂) = 6.01 moles Cl

There are 6.01 moles of Cl atoms in 1.81*10^24 formula units of MgCl₂.

Ch4 is nonpolar and insoluble in water. since all of the hydrogen atoms are evenly spread around the carbon atom even through the c h bond is polar all the poles cancel each other out.