Here's what I got.
The idea here is that you need to use a conversion factor that can take you from number of molecules to moles.
This conversion factor is called Avogadro's number and it's actually the definition of a mole.
In simple terms, a mole is just a very, very large collections of atoms or molecules, depending on what substance you're dealing with.
In order to have one mole of a substance, you need to have a fixed number of atoms of that substance. More specifically, you need to have
#color(blue)(|bar(ul(color(white)(a/a)"1 mole" = 6.022 * 10^(23)"atoms"color(white)(a/a)|))) ->#Avogadro's number
How many moles are in *
#1 xx 10^(24)#atoms of sodium?*
So, you know that a mole is defined as a collection of
#1 * 10^(24)color(red)(cancel(color(black)("atoms Na"))) * overbrace("1 mole Na"/(6.022 * 10^(23)color(red)(cancel(color(black)("atoms Na")))))^(color(blue)("Avogadro's number")) = "1.66 moles Na"#
You need to round this off to one sig fig, the number of sig figs you have for the number of atoms of sodium
#"no. of moles" = color(green)(|bar(ul(color(white)(a/a)color(black)("2 moles Na")color(white)(a/a)|)))#