1. A partially opened mine door can be use as a regulator.

2. The specific gravity of normal air is _________.

3. For exploration, if at all possible, entry into the mine should be made:

4. A regulator can be made by knocking blocks out of a permanent bulkhead.

5. After an explosion has occurred, the hazards a team might encounter are:

6. The explosive range and flammability of ethane in normal air is:

7. A pitot tube is used to measure the direction and velocity of slow moving air.

8. Dinner buckets encountered during exploration are important because:

9. ____________________ is a mixture of carbon dioxide, nitrogen, and air.

10. A smoke tube is a device that emits a smoke cloud which floats along with the air current to show the direction of the airflow and the approximate velocity.