Science, in the broadest sense, can be viewed as our continuing attempt to organize and describe the properties of nature. because this is an infinitely vast subject, science is subdivided into various disciplines, such as chemistry, biology, geology, and physics. chemistry is the branch of science that studies the properties and interactions of matter.

1. emigration the movement of people from one place to another 2. immigration a situation in which resources are being used up at a faster rate than they can be replenished 3. migration the leaving of one's homeland to settle in a new place 4. overpopulation the movement of people to a new country 5. sustainable development a situation in which the birth rate is not sufficient to replace the existing population 6. underpopulation the ability to meet current needs without reducing the ability to meet future needs 7. unsustainable development the increase in the population of a city 8. urbanization a situation in which the number of people exceeds the available natural resources in an area