Select the correct answer.

the periodic table houses noble gas elements in group 18. these elements are highly stable and rarely react with any other elements. what is one possible reason for the stability of the noble gas elements?

a.

they easily form covalent bonds.

b.

the compounds that they form with other elements are very unstable.

c.

their outermost shell has the maximum number of electrons that it can hold.

d.

they require less activation energy

Which statements describe resources? one of the factors people use when deciding where they will live is the availability of resources. renewable resources have little value for people. resources are unevenly distributed throughout the world. energy is the world resource which has the highest use. the use of nonrenewable resources has decreased in recent history. the use of resources is evenly distributed throughout the world. the world's oil supply will last for the next forty years if its use continues as expected.

Explain how scientists use geologic time to determine the age of landforms.

This is a typical grassland food web. it is also a small picture of an important cycle on earth: the carbon cycle. describe how the carbon gets into this food web. a) bacteria and fungi, the decomposers, recycle carbon from dead organisms. b) carbon is found in the grass and is passed from one level to the next in this food web. eliminate c) all living things give off carbon dioxide as a by-product of respiration and it is released into the atmosphere. d) plants use carbon dioxide as a reactant in photosynthesis, to make usable chemical energy in the form of a sugar.