N,P,As,Sb and Bi belong to the group? Which element does not show allotropy form? Covalency of 3 and 5 is shown by? Which is a reducing agent? Which substance acts as both oxidizing and reducing agent? Phosphorus can for phosphorus penta chlorine but nitrogen cant do this because? Which is the stable form of phosphorus? Which one is most reactive form of phosphorus? Which is incorrect about phosphorus? Which is not ore of sulphur?