Khan academy Test UPDATED ACTUAL
Questions and CORRECT Answers
In an experiment, acid was added to two solutions:
Solution 1: distilled water only
Solution 2: distilled water containing sodium bicarbonate
Then, the pH of each solution was taken.
Solution 1 had a final pH of 4.5, while Soluti...
Khan academy Test UPDATED ACTUAL
Questions and CORRECT Answers
In an experiment, acid was added to two solutions:
Solution 1: distilled water only
Solution 2: distilled water containing sodium bicarbonate
Then, the pH of each solution was taken.
Solution 1 had a final pH of 4.5, while Solution 2 had a final pH of 6.8.
Which of the following statements explains the difference between the two solutions?
(Choice A,
A
Sodium bicarbonate increases the temperature of a solution, which helped raise the pH of
Solution 2.
(Choice B)
B
Hormones released in Solution 2 allowed it to maintain a higher pH.
(Choice C)
C
The water in Solution 1 had a lower starting pH than the water in Solution 2.
(Choice D)
D
Sodium bicarbonate acted as a pH buffer in Solution 2. - CORRECT ANSWER✔✔- Sodium
bicarbonate acted as a pH buffer in Solution 2.
Which of the following describes surface tension in water? - CORRECT ANSWER✔✔-
Surface tension allows water to support small objects if they are placed carefully on its
surface.
, Surface tension is the tendency of a liquid's surface to resist rupture when placed under
tension or stress. If a small object is placed carefully on its surface, the tension created by the
hydrogen bonds in the water can often prevent the object from sinking.
Water is important to all living things.
How does the high heat capacity of water help support life?
Choose 2 answers: - CORRECT ANSWER✔✔- 1. It allows animals to have highly regulated
internal body temperatures.
Water's heat capacity helps warmblooded animals distribute heat through their bodies in a
regulated manner.
2. It makes water a great habitat for marine life because marine organisms do not experience
a wide temperature range.
Many organisms cannot handle drastic changes in temperature, and water prevents this from
happening due to its high heat capacity.
Allen pours water into a graduated cylinder. He notices that the surface of the water is curved,
as shown below.
Graduated cylinder showing curved surface of water where the sides of the water are higher
than the center
Graduated cylinder showing curved surface of water where the sides of the water are higher
than the center
Which of the following identifies this phenomenon and explains how it is formed? -
CORRECT ANSWER✔✔- curved surface- capillary action
Why is water unable to dissolve substances like oil? - CORRECT ANSWER✔✔- Water is
polar and oil is nonpolar.
Because water is polar and oil is nonpolar, their molecules are not attracted to one another.
Polar molecules are attracted to other polar molecules while nonpolar molecules are attracted
to other nonpolar molecules. This concept is often stated as, "Like dissolves
like."Autoionization occurs when a neutral molecule ionizes into anion and a cation.
Which of the following equations best illustrates the autoionization of water?
Autoionization occurs when a neutral molecule ionizes into anion and a cation.
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