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# Which element behaves chemically both as metal and non-metal ?

[ A ]    Argon
[ B ]    Carbon
[ C ]    Xenon
[ D ]    Boron
 Answer : Option D Explanation : Boron was discovered by Joseph Louis Gay – Lussac and Louis Thenard on 30 June 1808. It is known as very hard element. It is a black and semimetallic element. Boron is used as rocket fuel. It is used to produce borosilicate glass and is used as a controller of nuclear reactors.