<prompt> Least amount of co2 is inAnatomical dead space-end inspiration phaseAnatomical dead space-end expiration phaseAlveoli-end inspiration phaseAlveoli-end expiration phase  <response>: Ans. a Anatomical dead space-end inspiration phaseRef: Ganong, 25th edp.630Anatomical dead space containing atmospheric air at the end of inspiration will have the least amount of CO2 - because atmospheric air has negligible CO2 Anatomical dead space-end expiration phase: Here alveolar gas rich in CO2 occupies the Anatomical dead space dead space areaAlveolar air contains a mixture of O2 from the inspired air and CO2 which is continuously added to it to exhale out 