1.Sitting cross-legged on the ground II. Lying horizontally flat on the ground
III. Standing on both feet and not moving
IV. Seated motionless on a rocking chair with both feet on the ground

Gravitational potential energy is the energy stored in a body due to its heightfrom the ground. The amount of gravitational potential energy a person has depends on the distance of his centre of mass from the ground. Given that a person's centre of mass is at his navel (just below his stomach), arrange the
positions, I, II, III and IV, in the order that will give the person an increasing
gravitational potential energy.
[1]​

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.