Question

calculate the mass in grams of 250ml of NO2 at STP​

Answer 1

At STP - Standard Temperature and Pressure (273.15K, 1 atm) - an ideal gas' molar volume is equal to 22.4L. This means that 1 mole of any ideal gas always occupies that volume at that pressure and that temperature.

Now, even before calculating the actual value, one must try and estimate what that value could be; since we were given 99.02L, it's fairly easy to see that we must be dealing with more than 1 mole.

SInce 22.4 is between 4 and 5 times smaller (more than 4, less than 5) than 99.02, we could estimate the number of moles to be 4.5, which, given NO2's molar mass of 46gmol, would result in 207g.

The actual number of moles is

nNO2=VVmolar=99.02L22.4L=4.42 moles, which means

mNO2=n⋅molarmass=4.42moles⋅46gmole=203g

please mark this answer as brainalist and follow me