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

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

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

altitude