Q: What results when a warm air mass runs into a cold air mass?   A:
OPTIONS:
- cool front
- dry front
- rough front
- warm front

Answer: warm front


Q: Which form of digestion is a purely physical process that does not change the chemical nature of the food?   A:
OPTIONS:
- slow
- simple
- electromagnetic
- mechanical

Answer: mechanical


Q: Density and pressure of air decreases with what?   A:
OPTIONS:
- temperature
- humidity
- horizontal distance
- altitude

Answer:
altitude