1. The graph below shows the winter precipitation in Arizona from 1995 to 2002. It also shows the survival rates of Arizona pronghorn fawns for
the same period.
Precipitation and Arizona
Pronghorn Fawn Survival
90
90
80
80
70
70
60
-
60
50
50
Precipitation (cm)
Fawns/100 Females
40
40
30
30
20
20
10
10
0
→
1995 1996 1997 1998 1999 2000 2001 2002

because natural gas is colorless, odorless, and tasteless, distributors add mercaptan (a chemical that smells like sulfur) to give natural gas a distinct unpleasant odor (it smells like rotten eggs). they locate the types of rock that are likely to contain natural gas deposits.

it's c (engineer's do their work with mechanical stuff not on any living being)

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.