| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.11 |
| Score | 0% | 62% |
Which of the following substances gives up positively charged hydrogen ions (H+) when dissolved in water?
base |
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acid |
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alkaline |
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solution |
An acid is a substance that gives up positively charged hydrogen ions (H+) when dissolved in water. A base (alkaline) gives up negatively charged hydroxide ions (OH-) when dissolved in water. pH is a scale that measures of how basic or acidic a solution is. Numbered from 0 to 14, solutions with a pH of 7 are neutral, less than 7 are acidic, more than 7 are alkaline.
These clouds grow upward and can develop into cumulonimbus or thunderstorm clouds.
cirrus clouds |
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nimbus clouds |
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stratus clouds |
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cumulus clouds |
Cumulus clouds are large, puffy, mid-altitude clouds with a flat base and a rounded top. These clouds grow upward and can develop into a cumulonimbus or thunderstorm cloud.
Changes to an object's speed or direction of motion are caused by which of the following?
a force |
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kinetic energy |
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power |
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work |
Force is applied to change an object's speed or direction of motion.
What part of the nervous system is responsible for controlling involuntary actions like breathing, swallowing, and heartbeat?
cerebellum |
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medulla |
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cerebrum |
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spinal cord |
Part of the brainstem, the medulla is the connection between the brain and the spinal cord. It controls involuntary actions like breathing, swallowing, and heartbeat.
Which of the following is not a characteristic of the Sun?
formed 2.6 billion years ago |
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is a yellow dwarf star |
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makes up over 99% of the mass of the solar system |
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is composed of hydrogen and helium |
The Sun is a G-type main-sequence star (G2V) but is informally known as a yellow dwarf star. Composed of 73% hydrogen and 25% helium, the hot plasma that makes up the Sun reaches 9,900°F (5,505°C) at the surface. It formed approximately 4.6 billion years ago and makes up 99.86% of the mass in the solar system.