1- four single bonds, 2- two single and one double bond, 3- one single and one t<span>riple bond, 4- two double bonds.</span>
C. the answer is c. i just took this test on keystone (i think this is keystone question. right?0
Answer: As matter cycles and energy flows through living systems and between living systems and the physical environment, matter and energy are conserved in each change. The carbon cycle provides an example of matter cycling and energy flow in ecosystems.
Explanation:
It entera from your body to the middle and then to the back and again.
