How many times stronger is the hydrogen-ion concentration of a pH 4 solution as compared with a pH 9 solution?
A. 0.00001
B. 5
C. 100,000
D. 50
The correct answer is c. 100,000. The pH scale is a logarithmic scale, which means that each change of one pH unit represents a tenfold change in the hydrogen-ion concentration. A pH 4 solution has a hydrogen-ion concentration that is 10^5 (or 100,000) times greater than that of a pH 9 solution.
a. 0.00001 is the hydrogen-ion concentration of a pH 9 solution as compared with a pH 4 solution.
b. 5 is the difference in pH units between a pH 4 solution and a pH 9 solution.
d. 50 is not the correct answer.
Therefore, the Correct Answer is C.
More Questions on TEAS 7 Science
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Q #1: Genetic information describing the characteristics of an organism is found in which of the following?
A. Nuclei
B. Membranes
C. Cilia
D. Ribosomes
Answer Explanation
The correct answer is a. Nuclei. Genetic information describing the characteristics of an organism is found in the nuclei of its cells. The nucleus contains the organism's DNA, which carries the genetic information that determines its traits.
b. Membranes are structures that surround and enclose cells and organelles, but they do not contain genetic information.
c. Cilia are hair-like structures that protrude from the surface of some cells and are involved in movement, but they do not contain genetic information.
d. Ribosomes are organelles that are involved in protein synthesis, but they do not contain genetic information.
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Q #2: The triple point of a substance is the temperature and pressure at which the substance exists as which of the following?
A. Simultaneously in sol, gel, and plasma phases
B. As a gel with solid and liquid trapped in gas
C. As a sol with gas and solid trapped in liquid
D. Simultaneously in solid, liquid, and gas phases
Answer Explanation
The triple point of a substance is the temperature and pressure at which the substance exists simultaneously in solid, liquid, and gas phases ¹. In thermodynamics, the triple point of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium.
The other options are not correct because they do not accurately describe the triple point of a substance. Sol, gel, and plasma are not phases that coexist at the triple.
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Q #3: Which of the following terms describes the relaxation of the chambers of the heart during the cardiac cycle?
A. Tachycardia
B. Diastole
C. Systole
D. Bradycardia
Answer Explanation
The relaxation of the chambers of the heart during the cardiac cycle is called diastole ¹. The cardiac cycle is a sequence of events that occurs when the heart beats ². It consists of two phases: systole, when the heart contracts and pumps blood into circulation, and diastole, when the heart relaxes and fills with blood ².
The other options are not correct because they do not accurately describe the relaxation of the chambers of the heart during the cardiac cycle. Tachycardia is a rapid heart rate, bradycardia is a slow heart rate, and systole is the contraction of the heart chambers.
