Which of the following is a physical property of sodium chloride It dissolves in water
It melts
at a high temperature
It is not significantly compressible
It is a solid at room temperature
All of the above are physical properties of sodium chloride

all of the above.

May be correct answer.

"the periodic table is arranged in order of atomic number."

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.