If 175 undecayed nuclei remained from a sample of 2800 nuclei, how many half-lives has passed? *

Aphysical change is one that you can put in and remove like a ham sandwich. the stuff you put in there can be changem its not permanet. a chemical change is on that can't be change thats permanet. like when you make a cake and bake it. you can't get those ingredients back.

Answerstrong acids and bases completely dissociate in water.this is how strong acids and bases are defined. they will ionize 100% in solution, making a non-reversible reaction

Answerchemical energy;