Mendeleev spent a great deal of time in laboratories as a student, studying the burgeoning new field of

Mendeleev spent a great deal of time in laboratories as a student, studying the burgeoning new field of CHEMISTRY.

Explanation:

Dmitri Mendeleev was a 'Russian chemist' and  also an inventor. He is known for formulating periodic law. He is also remembered for creating a version of periodic table consisting of  elements. He not only corrected the hypothesised properties of already discovered elements using a periodic table rather gave a prediction of properties of eight elements  are yet to be identified.  

The original draft about the discovery of the periodic table was published as "Tentative System of Elements". He is also known as remembered the "Father of  periodic table".  

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