Sentence:  **f appeared to be well suited for the study of these matters , since it is a <WSD>normal</WSD> paramagnet , with three unpaired electrons on the chromium , its crystal structure is very simple , and the unknown position of the hydrogen in the strong **f bond provides structural interest . 
Meaning of the word marked with <WSD> tags:  conforming with or constituting a norm or standard or level or type or social norm; not abnormal