All of the rivers in the United States are not monitored closely for pollution levels.
The statement in the question is False
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Explanation:</u></h3>
Not all rivers in the United States are closely monitored for their pollution levels. There are volunteers who take responsibility of checking water bodies such as lakes, rivers, streams etc. They take the next step required after finding a water body contaminated.
But to say that all the rivers receive the same amount of attention and action is incorrect. To ensure that all the rivers are clean and pollution free, it would require a lot of man power in the said department which would collect the water samples from all these rivers and send it to labs for checking the pollution level of the particular river. It can be said that the rivers which are situated beside an industrial site, close to a town, will be the priority for checking pollution levels as it would directly cause harm to a small set of population if the toxicity is at an increased level.
Explanation :
It is given that, the driver accelerates from a stop sign, cruises for 20 s at a constant speed of 60 km/h, and then brakes to come to a stop 40 s after leaving the stop sign.
We know that acceleration is defined as the rate of change of velocity.
Where
dv is the change in velocity, dv = 0 - 60 m/s = -60 m/s
dt is the change in time, dt = 40 s - 30 s = 10 s
So, 
From the graph it is clear that, from 30 s to 40 s the car is decelerating. So, at every second within this time the value of acceleration will be same i.e. 
.
Answer:
It does not hit the students face because the speed of the balloon slows down as energy is lost through thermal.
Explanation:
I think you would be using a topographic Map, So the answer should be A
