Phosphorus has three electrons in its 3p sublevel and sulfur has four. phosphorus should have the lower ionization energy but it does not, sulfur does. why? a. phosphorus has 2 of its electrons paired in the 3p sublevel, which makes them harder to remove, or "ionize." b. sulfur has 2 of its electrons paired in the 3p sublevel. the mutual repulsion of their negative charges makes them easier to remove, or "ionize." c. because sulfur has more electrons, they are further from the nucleus and thus easier to remove and form an ion. d. since sulfur has more electrons, it has more chances to form an ion.

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.