| Questions | 5 |
| Topics | Acidity, Base Units, Cirrus Clouds, Cumulus Clouds, Filtering Air |
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.
| Measurement | Base Unit | Example |
|---|---|---|
| length / distance | meter (m) | km |
| mass | gram (g) | kg |
| volume | liter (L) | mL |
| volume (medical) | cubic centimeter (cc) | cc |
| time | second (s), minute (min), hour (h) | ms, min, h |
| temperature | centigrade (°C) | °C |
Cirrus clouds are thin, wispy high-altitude clouds composed of ice crystals that originate from the freezing of supercooled water droplets. Cirrus clouds generally occur in fair weather and point in the direction of air movement at their elevation.
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.
After air enters through the nose, it passes through the nasal cavity which filters, moistens, and warms it. Further filtering takes place in the pharynx, which also helps protect against infection, and then in the trachea which is just past the epiglottis, responsible for preventing food from entering the airway.