If I had dilute Sodium hydroxide solution dropwise until in excess to a solution containing X ions, and I observed a green precipitate soluble in excess to form a green solution. I added few drops of Hydrogen peroxide solution, and I observed a yellow precipitate of Y ions. I added Butan-1-ol followed by dilute Sulphuric acid and formed a blue solution of M ions in organic layer.
State the ions;
(a). X
(b). Y
(c). M
[✓Hint: Think of confirmatory test of Chromium ions]

i think   the answer is c hope i'm right

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.