Yes, people should be concerned because plaque buildup might cause your breath to smell bad, or cause your teeth to look very yellow, consider brushing your teeth and using mouth wash daily and don’t drink or eat unhealthy foods that will cause your teeth to look bad. plaque buildup might also cause damage to the stomach and maybe affect when you have to use the restroom.
Rust is when a metal turns brown-ish red-ish and that tells you that the metal is old and is no longer useful. we don't want it floating in our bodies because it's rusted metal. hope this helped! :)
The molar mass or As is 74.9g. Start with 281g multiply by (1mol/74.9g) = 3.75 mols
Put what you don’t want on the bottom (in this case grams) so they the u it’s cancel (if you multiply by grams and the divide by grams they cancel. Ultimately leave what you want on the top ( This case mols) then do the math