The density of a 20.3 m ch3oh (methanol) solution is 0.858 g/ml. what is the molality of this solution? h2o is the solvent.
a. 17.4 m
b. 20.8 m
c. 23.7 m
d. 70.0 m
e. 97.6 m

The difference of molarity and molality is in the units:

Molarity is expressed in mol solute / L solution;

 while Molality is expressed in mol solute / kg solvent

Since no other data is given, let us assume that the contribution of methanol on the total volume is negligible. So that,

Molality = (20.3 mol / L) (1 L / 0.858 kg)

Molality = 23.66 m

The closest answer is letter C. 23.7 m

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.