Which of the following is TRUE? A. The equivalence point is where the amount of acid equals the amount of base during any acid-base titration.
B. At the equivalence point, the pH is always 7
C. An indicator is not pH sensitive
D. A titration curve is a plot of pH vs. the [base]/[acid] ratio
E. none of these is true

D. a titration curve is a plot of pH vs. the [base]/[acid] ratio

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.