If 5 moles of Al2O3 are formed in the reaction " 4 Al + 3 O2 ---> 2 Al2O3 " How many moles of Aluminum (Al) & How many moles of Oxygen (O2) are consumed in the reaction?

We are given the reaction:

4 Al + 3 O₂ → 2 Al₂O₃

Finding moles of Al reacted:

from which, we can deduce that 4 moles of Al produces 2 moles of Al₂O₃

Ratio between their moles:

Moles of Al / Moles of Al₂O₃

4 / 2 = 2 / 1

so,

Moles of Al / Moles of Al₂O₃ = 2

Moles of Al = 2* Moles of Al₂O₃

we are given that 5 moles of Al₂O₃ are formed, replacing the value:

Moles of Al = 2*5

Moles of Al = 10 moles

Finding moles of O₂ reacted:

from the given equation, we can also say that 4 moles of Al react with 3 moles of O₂

Moles of Al / Moles of O₂ = 4 / 3

3 * (Moles of Al) = 4* (Moles of O₂)

we know that 10 moles of Al reacted,

3 * (10) = 4 * (moles of O₂)

Moles of O₂ = 30/4

Moles of O₂ = 7.5 moles

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.