Why spores and inactive cells aredifficult to kill with a disinfectant..?

Question

thanks for your serious and polite answers.

Answer 1

Some types of bacteria form like anthrax form spores that are impervious to many chemicals.

http://en.wikipedia.org/wiki/Endospore

Answer 2

Endospores are resistant to heat and require autoclaving to kill them. Some microbial cells can revert to endospores in adverse conditions and revert to the vegetative cells when conditions are more favourable.

Hope this helps!