How many moles are present in 4.50 L of fluorine gas (F2) at Standard Temperature and
Pressure?

4.50 L gas of fluorine at STP contain 0.2 moles.

Explanation:

Given data:

Volume of gas = 4.50 L

Number of moles F₂ gas  = ?

Temperature of gas = standard =  273.15 K

Pressure of gas = standard = 1  atm

Explanation:

Formula:

PV = nRT

P= Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

Now we will put the values in formula.

1 atm × 4.50 L = n × 0.0821 atm.L/ mol.K  × 273.15 K

4.50 atm.L  = n × 22.43 atm.L/ mol.

n = 4.50 atm.L   / 22.43 atm.L/ mol.

n = 0.2 mol

4.50 L gas of fluorine at STP contain 0.2 moles.

object b by 0.42g/cm cubic

Explanation:

density = mass/volume

object a =10/8

=1.25g/cm^3

object b = 10/6

=1.67g/cm^3

therefore object b has greater density and by 0.42g/cm^3 (1.67- 1.25)