apathy vs inertness

apathy

noun
  • Lack of emotion or motivation; lack of interest or enthusiasm towards something; disinterest (in something). 

inertness

noun
  • Lack of activity or exertion; habitual indisposition to action or motion 

  • Absence of the power of self-motion; inertia. 

  • Quality of being unreactive with other chemical compounds or elements. 

How often have the words apathy and inertness occurred in a corpus of books? (source: Google Ngram Viewer )