Which of the following is an element? A. Fire B. Carbon C. Salt D. Water

OPTION B is correct

Carbon

Explanation:

element can be defined as a pure substance which cannot be broken down by into smaller units through a chemical method, an element has atoms with identical numbers of protons in their atomic nuclei

Each element is composed of its own type of atom. And this gives the reason why chemical elements are all very different from each other. And all substance on Earth has atoms of at least one of this elements.

There about 118 elements and all arranged in a row and colomn of the periodic table .This elements of the periodic table are arranged by their atomic number, which helps with the chemical properties. Example of elements are; Hydrogen, Oxygeñ, carbon.

Therefore, among the option only carbon is an element because it cannot be broken down into smaller unit unlike water which is made up of oxygen and hydrogen. Also salt is a compound containing more elements.

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.