Bohr produced an early model of the atom. Bohr’s model was eventually replaced by the cloud model of the atom. What is the main reason scientists use a model of an atom?

Group of answer choices

An atom is very small, and a model aids in its study.

All atoms are too dangerous to study without a model.

Most atoms are too far away for scientists to study in a lab.

Most atoms are too large to study in a lab.

In an experiment examining the effects tai chi on arthritis pain, callahan (2010) selected a large sample of individuals with doctor-diagnosed arthritis. half of the participants immediately began a tai chi course and the other half (the control group) waited 8 weeks before beginning. at the end of 8 weeks, the individuals who had experienced tai chi had less arthritis pain that those who had not participated in the course.