ACT真題每日一練8.20

　　Science Question for Thursday, August 20th, 2015

　　Passage I

　　The following table represents the concentration of ions and dissolved gases in the sediment at the bottom of an ocean. A depth of 0 centimeters (cm) represents the top of the sediment. The concentrations are expressed in parts per million (ppm). The acidity of a solution is represented on a scale known as pH. A pH of 1 is very acidic, a pH of 7 is neutral, and a pH of 14 is very basic.

　　Table adapted from R.M. Atlas and R. Bartha, Microbial Ecology: Fundamentals and Applications.

　　©1981 by Addison-Wesley Publishing Company.

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　　A certain type of bottom-dwelling microorganism thrives under the following environmental conditions: low concentrations of Fe2+, high concentrations of O2, and a neutral pH. Based on the table, at which of the following sediment depths would one most likely find this microorganism?

　　F. 0 cm

　　G. 5 cm

　　H. 10 cm

　　J. 15 cm