What is the mean free path for the molecules in an ideal gas when ...

[penguins]

What is the mean free path for the molecules in an ideal gas when the pressure is 100 kPa and the temperature is 300 K given
 
  that the collision cross-section for the molecules of that gas is 2.0  10-20 m2? Boltzmann's constant is k = 1.38  10-23 J/K.
  A)
 
  1.1  10-6 m
 
  B)
 
  2.1  10-6 m
 
  C)
 
  1.7  10-6 m
 
  D)
 
  5.3  10-6 m
 
  E)
 
  1.5  10-6 m

Question 2

Luminous (normal) matter makes up approximately what percentage of the known matter in the universe?
 
  A) 15 B) 5 C) 60 D) 95

[SomethingSomething]

Answer to Question 1

E

Answer to Question 2

A

[penguins]

Thanks for the timely response, appreciate it

[upturnedfurball]

Gracias!