| Questions | 5 |
| Topics | Acidity, Base Units, Number System, Periods, Stationary Front |
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 |
The metric system is a number system that designates one base unit for each type of measurement. For example, the base unit for length is the meter and the base unit for mass is the gram.
The rows of the Periodic Table are called periods and contain elements that have the same number of electron shells ordered from lower to higher atomic number.
When two air masses meet and neither is displaced, a stationary front is created. Stationary fronts often cause persistent cloudy wet weather.