About 2% of our solar nebula consisted of elements besides hydrogen and helium. However, the very firstgeneration of star systems in the universe probably consisted only of hydrogen and helium. Which of the followingstatements is most likely to have been true about these first generationstar systems?A. Jovian planets in these first generationstar systems had clouds made of water and other hydrogen compounds. B. These first generation star systems typically had several terrestrial planets in addition to jovian planets. C. There were no comets or asteroids in these first generation star systems. D. Like the jovian planets in our solar system, the jovian planets in these first generationsystems were orbited by rings.

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.