In which natural cycle must an important gas in earth's atmosphere be fixed before plants can use it?
a. sulfur cycle
b. carbon cycle
c. nitrogen cycle
d. oxygen cycle

Which of the following list the divisions of the geologic time scale in order from longest to shortest

Which is a substance that can be separated by physical means and is not the same throughout

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?