Which of the following is correct regarding the pH scale?
A substance with a pH of 3 is two times more alkaline than a substance with a pH of 4.
A substance with a pH of 3 is two times more acidic than a substance with a pH of 4.
A substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4.
A substance with a pH of 3 is 10 times more alkaline than a substance with a pH of 4.
The Correct Answer is C
The pH scale is a logarithmic scale that measures the acidity or alkalinity of a solution.
A solution with a pH of 7 is neutral, while a solution with a pH less than 7 is acidic and a solution with a pH greater than 7 is alkaline.
Because the pH scale is logarithmic, each whole number change in pH represents a tenfold change in acidity or alkalinity.
Therefore, a substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4.
Choice A. A substance with a pH of 3 is two times more alkaline than a substance with a pH of 4 is not correct because it incorrectly states that the substance with a lower pH is more alkaline and also incorrectly states the magnitude of the difference in acidity or alkalinity.
Choice B. A substance with a pH of 3 is two times more acidic than a substance with a pH of 4 is not correct because it correctly states that the substance with a lower pH is more acidic but incorrectly states the magnitude of the difference in acidity.
Choice D. A substance with a pH of 3 is 10 times more alkaline than a substance with a pH of 4 is not correct because it incorrectly states that the substance with a lower pH is more alkaline.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Diffusion down a concentration gradient causes most of the carbon dioxide from the blood to move into the alveoli.
The alveoli are tiny air sacs in the lungs where gas exchange occurs.
Carbon dioxide is a waste product of cellular respiration and is carried by the blood to the lungs to be exhaled.
In the lungs, carbon dioxide diffuses from the blood (where its concentration is high) into the alveoli (where its concentration is lower) down its concentration gradient.
Choice A is incorrect because carbon dioxide is not converted to carbon monoxide in the body.
Choice C is incorrect because passive transport using carrier proteins is not the primary mechanism by which carbon dioxide moves from the blood into the alveoli.
Choice D is incorrect because active transport using energy is not involved in the movement of carbon dioxide from the blood into the alveoli.
Correct Answer is C
Explanation
In the human body, maintaining the pH of the blood within a narrow range is critical for proper physiological functioning.
One of the buffering systems that helps to regulate blood pH involves the conversion of carbon dioxide (CO2) and water (H2O) into carbonic acid (H2CO3), which then dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-).
Carbonic acid (H2CO3) is responsible for donating H+ ions to act as a buffer when blood pH rises.
When blood pH rises (becomes more alkaline), carbonic acid dissociates, and the H+ ions combine with bicarbonate ions to form more carbonic acid.
This helps to remove excess H+ ions from the blood and prevent the pH from rising too much.
Option A, carbon dioxide, is involved in the buffering system through its conversion to carbonic acid.
However, it does not directly donate H+ ions to act as a buffer when blood pH rises.
Option B, carbon monoxide, is a toxic gas that binds to hemoglobin in red blood cells, preventing them from carrying oxygen.
It is not involved in the buffering system and does not donate H+ ions.
Option D, oxygen, is carried by hemoglobin in red blood cells and is essential for respiration.
It is not involved in the buffering system and does not donate H+ ions.
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