activity vs inertness

activity

noun
  • The lexical aspect (aktionsart) of verbs or predicates that change over time and have no natural end point. 

  • Something done as an action or a movement. 

  • Something done for pleasure or entertainment, especially one involving movement or an excursion. 

  • The state or quality of being active; activeness. 

  • The number of radioactive decays per unit time. Unit for it: becquerel or curie 

  • The propery of substances to react with other substances 

inertness

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

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

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

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