Human activity causes changes to the groundwater and surface water in a watershed. Which change to groundwater or surface water is classified as a chemical change? A: Concrete streets and parking lots cause more water to remain surface water instead of absorbing into the ground to become groundwater.

B: Hydroelectric dams built on rivers create lakes upstream of the dams and variable flow downstream.

C: Industrial waste that is dumped in a river causes acidic conditions that cause damage to fish digestive systems.

D: Rainwater collects in drainage ditches and flows to nearby lakes, increasing the water volume in lakes.
SUBJECT: Science

Asmall (but heavy) particle placed in a glass of water will follow a zigzag motion because the particle will bounce off of the water molecules it meets. this is called brownian motion. a physicist simulates this on a computer, by varying the distance a particle can travel (called the mean free length), on average, before it collides with a water molecule and assigning the change in motion to be one of 8 directions, each with a similar probability. by running the simulated particle (with the same mean free length) many times she determines that it should take 15 seconds, on average, for the particle to fall to the bottom, with a standard deviation of 1.5 seconds. next she lets a real particle fall through a glass of water and finds that it took 18 seconds. what does she conclude, and why?

For which of the following counts would a binomial probability model not be reasonable? a)the number of people in a classroom born in januaryb) the number of people in a classroom with red hair c) the number of people admitted to a hospital in a day with a particular disease d) the number of heart beats in a one-minute perio.

How does a low unemployment rate affect a nation's economy? a. the nation has a higher number of productive resources. b. the nation can spend more money on for unemployed people. c. the nation can save money by paying lower salaries to a large workforce. reset