Typical room is 4.0 m long, 5.0 m wide, and 2.5 m high. what is the total mass of the oxygen in the room assuming that the gas in the room is at stp and that air contains 21% oxygen and 79% nitrogen?

mass of oxygen gas in Kg = 15.0Kg

Explanation:

Volume of air in the room = 4.0m*5.0m*2.5m = 50m³

volume of oxygen in the room = 21/100 *  50m³ = 10.5m³

using the ideal gas equation; PV=nRT

number of moles of oxygen gas, n = PV/RT

At STP, P = 1atm, V = 10.5m³ = (10.5*1000)dm³ = 10500dm³, R = 0.082 atmdm³K⁻¹mol⁻¹, T = 273K

n = 1 * 10500/ (273 *0.082)

n = 469.04 moles

mass of oxygen gas in Kg = (no of moles * molar mass)/1000

molar mass of oxygen gas = 32g

mass of oxygen gas in Kg = (469.04 * 32)/1000

mass of oxygen gas in Kg = 15.0Kg

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.