7. In a controlled process called cracking, small short-chain hydrocarbons are produced from
A water and carbon dioxide
B tough plant products such as wood
C large, long-chain hydrocarbons
D natural gas

its temperature is increasing. this causes molecular vibrations to increase.

in the year 2850, humans successfully colonized mars. the martian modules that were constructed could hold only a small population of people. it is now a century later, and the population on mars has grown to 600 people. of the current mars population, 45 people express the recessive phenotype for phenylketon- uria (pku) syndrome (pp genotype).

explanation: