Materials: Reactions in our World Virtual Lab
Variables:
List your controlled variables, independent variable, and dependent variable for each
experiment in the chart below. Remember, controlled variables are factors that remain the
same throughout the experiment. An independent (test) variable changes so that the
experimenter can see the effect on other variables. The dependent (outcome) variable will
change in response to the test variable.
Chemical Reaction
Controlled
Variables
Independent
Variable
Dependent
Variable
Iron and copper (II) sulfate solution
Lead (II) nitrate and potassium iodide
solutions
Magnesium metal and hydrochloric acid
solution
Electrolysis of water
Burning magnesium

i think its 100

i hope this !

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.

a is the correct answer