Chlorine

The scientist who discovered and isolated the chlorine gas
Ans : Carl Scheele
The scientist who recognized chlorine as an element
Ans : Humphry Davy
The second element having highest reactivity
Ans : Chlorine
The colour of Chlorine gas 
Ans : Pale yellow green
The organic compound which contains chlorine
Ans : DDT, BHC, Chloroform, Freon 
Chloroform was discovered by 
Ans : James Young Simpson 
The poisonous substance produced when the chlorine is exposed 
Ans : Phosgene
The gas which was used as chemical weapon in the First World War 
Ans : Phosgene
The element used to purify