Which allotrope of phosphorus is the most reactive?

Which of the following noble gases do not occur in the elemental state in the atmosphere?

Which of the following compounds react with water to give phosphine?

All halogens form only one oxoacid due to their high electronegativity and small size.

What are the decay products of radium?

What are interhalogen compounds used as?

Which compound is used as a reducing bleach for papers

Which of the following is not poisonous?