Which of the following is correct regarding the pH scale?
A. A substance with a pH of 3 is two times more acidic than a substance with a pH of 4.
B. A substance with a pH of 3 is two times more alkaline than a substance with a pH of 4.
C. A substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4.
D. A substance with a pH of 3 is 10 times more alkaline than a substance with a pH of 4.
The pH scale is a quantitative measure of the concentration of hydrogen ions in a solution. It tuns from 1 to 14 and the pH values less than 7 signify a solution is acidic, while those values greater than 7 are basic or alkaline. A solution with a pH of 7 is neutral. The pH scale is logarithmic and every unit of pH corresponds tie 10-fold change in acidity. As the pH decreases, the acidity of the solution increases. Therefore, a solution with a pH of 3 is 10 times more acidic than a solution with a pH of 4.
Therefore, the Correct Answer is C.
More Questions on TEAS 7
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Q #1: Which of the following substances is responsible for donating H+ ions to act as a buffer when blood pH rises?
A. Carbon monoxide
B. Carbonic acid
C. Carbon dioxide
D. Oxygen
Answer Explanation
The physiological function of the body depends on the balance between the concentrations of acids and bases in the blood. For a better body function, the blood pH falls in the range of 7.45 and 7.35. beyond this point, the blood my become too acidic or basic and may have drastic effect on the physiologic function of the body. To maintain this blood at constant, the buffer system comes into play. It does not allow the pH to drop or increase drastically. From the properties of acids and bases, acids donate protons while bases are proton acceptors. In our bodies, there are three buffer systems:
- Carbonate/carbonic acid buffer
- Phosphate buffer
- Plasma proteins
Th carbonate/carbonic acid buffer plays a key role in acid-base balance in our bodies. This buffer system is regulated by the respiratory system. If there is less H ions on the system, the carbonic acid dissociates and donate H ions as show in the reaction below, which thus declines the pH of the blood.
H2CO3 + H2O ?
H3O+ + HCO3- -
Q #2: Which of these numbers best represents an alkaline solution?
A. 1
B. 6
C. 7
D. 12
Answer Explanation
Th pH scale runs from 0 to 14. Acid substances have pH values between 0 and 7 While alkaline solutions have pH values between 7 and 14. A neutral solution has a pH value of 7. Thus, from the question above, a pH value of 12 represent an alkaline solution.
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Q #3: Which of the following is correct regarding the pH scale?
A. A substance with a pH of 3 is two times more acidic than a substance with a pH of 4.
B. A substance with a pH of 3 is two times more alkaline than a substance with a pH of 4.
C. A substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4.
D. A substance with a pH of 3 is 10 times more alkaline than a substance with a pH of 4.
Answer Explanation
The pH scale is a quantitative measure of the concentration of hydrogen ions in a solution. It tuns from 1 to 14 and the pH values less than 7 signify a solution is acidic, while those values greater than 7 are basic or alkaline. A solution with a pH of 7 is neutral. The pH scale is logarithmic and every unit of pH corresponds tie 10-fold change in acidity. As the pH decreases, the acidity of the solution increases. Therefore, a solution with a pH of 3 is 10 times more acidic than a solution with a pH of 4.
