nder what reaction conditions does the electrophilic chlorination of aromatic compounds usually occur

Cl2/FeCl3

Explanation:

The electrophilic chlorination of aromatic compounds proceeds in the presence of Cl2/FeCl3.

The function of the Lewis acid FeCl3 is to 'activate' the chlorine molecule towards electrophilic substitution. This occurs by the formation of a 'chlorine cation' which attacks the aromatic ring followed by deprotonation of the aromatic ring to retain the aromaticity of the compound.

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.