A tank holds 125 moles of argon gas (atomic mass = 6.633521 × 10^-26 kg) at a pressure of 101300 Pa and a temperature of 301 K. Recall that the number of gas molecules is equal to Avagadros number (6.022 × 10^23) times the number of moles of the gas. Required:
a. What is the volume of the tank?
b. How much kinetic energy is contained in this gas?
c. What is the average speed of one of the argon atoms?
d. The escape speed of Earth is 11200 m/s. What temperature would the argon gas need to have so that the average speed of the gas atoms was equal to this escape speed?

ice to water 1 water to vapour 2 latent heat

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.