What is fossils used for?
a) determining the absolute age of rock
b) determining the relative agdd of rock
c) determining the type of rock
d) telling us how a rock layer was formed

Iron reacts with oxygen to produce iron oxide (rust). this reaction is represented in an equation as 4fe + xo2 → 2fe2o3. identify the value of x that will balance the equation.

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

Below, the levels of organization in a multicellular organism are shown from least to most complex. which level of organization can be described as several different types of tissues working together to perform a common task?