Answer
3.74 g/L
Work Step by Step
The atomic mass of an element is also the weight of one mole of that element. The atomic mass of krypton is 83.8 amu, so it weighs 83.8g for every 1mol: 83.8g/1mol. At STP (standard temperature and pressure) the volume of all ideal gases is 22.4L for every mole of gas. Thus, we can then combine these equations to eliminate mole and to get our answer in grams per liter.
