A 5.0-liter gas tank holds 1.4 moles of helium (He) and 0.70 ...

[Mr. Wonderful]

A 5.0-liter gas tank holds 1.4 moles of helium (He) and 0.70 moles of oxygen (O2), at a temperature of 260 K. The atomic masses of helium and oxygen are 4.0 g/mol and 16.0 g/mol, respectively.
 
  Avogadro's number is 6.022  1023 molecules/mol and the Boltzmann constant is 1.38  10-23 J/K. The total random translational kinetic energy of the gas in the tank is closest to
  A) 7.6 kJ. B) 6.8 kJ. C) 8.3 kJ. D) 6.1 kJ. E) 9.1 kJ.

Question 2

Two extremely large nonconducting horizontal sheets each carry uniform charge density on the surfaces facing each other. The upper sheet carries +5.00 C/m2. The electric field midway between the sheets is 4.25  105 N/C pointing downward.
 
  What is the surface charge density on the lower sheet? (0 = 8.85  10-12 C2/N  m2)

[chereeb]

Answer to Question 1

B

Answer to Question 2

-2.52 C/m2

[Mr. Wonderful]

TYSM

[laurnthompson]

Excellent