Which statement best describes how an existing theory is often affected by the development of new technology? An existing theory is thrown out and replaced with a completely new theory based on the new observations.
An existing theory is modified so that it can explain both the old and new observations.
An existing theory remains the same because a theory is a proven fact that is always true.
An existing theory is kept unchanged while a new theory is developed to explain the new observations.

A__ is two or more substances that are together in the same place but are not chemically combined

Answer asap need by wednesday morning explain how a buffer works, using an ethanoic acid/sodium ethanoate system including how the system resists changes in ph upon addition of a small amount of base and upon addition of a small amount of acid respectively. include the following calculations in your i. calculate the ph of a solution made by mixing 25cm3 0.1m ch3cooh and 40cm3 0.1m ch3coo-na+. [ka = 1.74 x 10-5 m] ii. calculate the ph following the addition of a 10cm3 portion of 0.08 m naoh to 500cm3 of this buffer solution. iii. calculate the ph following the addition of a 10cm3 portion of 0.08 m hcl to 200cm3 of the original buffer solution.

Is a chemical message sent by another individual.