Question

when was breathing rate is zero in human being....????

Answer 1

while in utero/ connected to the umbilical cord

Answer 2

no in embryonic stage our lungs were not active but we still braethe through placenta
breathing rate is minimum wen we sleep n zero wen we swallow the food by practical u can see wen u drink water u see bony box larynx move up {touch ur throat while drinking water or eating smthing will move up} n coverd by epiglotis to prevent food to go in repiratory tract at that time it is zero... :-)

Answer 3

but nice try ttom.. :-)