Three students are asked to discuss the sources of error that might have affected the outcome of the lab. Select the student that employs correct scientific reasoning. Student 1: If the spot was placed below the solvent level, this would cause the sample to be dissolved into the solvent pool before traveling up the plate. Student 2: If the solvent used has the opposite polarity of the stationary phase this will cause unequal movement of the sample. Student 3: If the developing chamber was closed too quickly than the sample wouldn't be able to travel on the TLC plate.

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.