In the chemical formula for magnesium chloride, mgcl what does the subscript 2 represent

The formula of manesium chloride (or magnesium chlorine) is:

In the formula, the number "2" represents the number of chlotine atoms that are bonded with one magensium atom.

In this case, there are 2 chlorine atoms for every magensium atom as shown in the image below.

Hope it helped,

BioTeacher101

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.