Ima chemist found the density of freon-11 (cfcl3) to be 5.58 g/l under her experimental conditions. her measurements showed that the density of an unknown gas was 4.38 g/l under the same conditions. what is the molar mass of the unknown?

If we assume this two gases behave like ideal gas, then we use the ideal gas law , where P is the pressure, V is the volume, n number of moles, R gas constant and T the temperature in kelvins. As well as the density formula . First we calculate the molarity for Freon

.

The number of moles for freon are

We know , so we insert this concept to our ideal gas equation

. Since , we insert this concept to the formula

. The measurements take place in same conditions so,

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.