Staining specimen with heavy metal salts (e.g. tungsten, molybdenum) allows you to see the specimen better with higher contrast when electron beam deflects off of your sample.
Answer : 135 grams of sodium has 5.869 moles.
Solution : Given,
Mass of sodium = 135 grams
Molar mass of sodium = 23 g/mole
Formula used :

Now put all the given values in this formula, we get

Therefore, the moles of sodium present in 135 grams of sodium is, 5.869 moles.