4. Anthracite coal, 1.0 g, produces 7.000 x 103 cal when burned. How many joules of energy does this represent? How many grams of anthracite are required to raise the temperature of 4.0 L of
water from 20.0 °C to 100.0 °C?

your parents i think this could be it

the answer is barium and copper bromide

може ли да зареждате повече информация, моля

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.