The astronaut's leaky suit tries to regulate oxygen and carbon dioxide levels, while maintaining total pressure. when the partial pressure to co2 rises too high, then a regulator opens a valve and vents air out of the suit. this triggers a low pressure problem, so the suit fills with nitrogen to maintain the atmospheric pressure at 1 atm. this triggers a low oxygen problem, so the suit adds a little oxygen. what do you suspect are the minimum oxygen and maximum co2 partial pressures that the suit tries to maintain? the answer is based on what you know from class about symptoms from low oxygen and high co2. pick the best answer.

see earlier answer

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.

it is a negative acceleration