2. Solid air pollutants called may reduce the energy available for photosynthesis.
3. If nitrogen and sulfur oxides dissolve in raindrops, the result is
rain.
4. Mercury and lead are examples of pollutants called
5. The pollutants in question 4 enter food chains from the
6. Acid rain has a pH value of less than
7. CFCs are human-made chemicals that contain the element

16

explanation:

the marks go by 4s

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.