An unknown gas has a density of 1.98 g/L. Calculate its molar mass and determine what gas it is from the table.
gas
molar mass
carbon dioxide
44
oxygen
32
nitrogen
28
helium
4
oxygen
O carbon dioxide
nitrogen
O helium

The number at the end of an isotope’s name is the number.

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.

Which proportionality applies to avogadro’s law?