1. If you know the specific gravity of a gas, you will know where it will be located in the mine and where you should test for it.

2. It is much easier to remove a concentration of sulfur dioxide by ventilation than it is to remove the same concentration of hydrogen.

3. During recovery of previously sealed areas, walking through water can result in the release of soluble gases that would not normally be in the mine atmosphere.

4. The degree to which a toxic gas will affect you depends on:

5. If you wear your self-contained breathing apparatus in petroleum based fumes for prolonged or successive periods, the fumes can eventually permeate its rubber parts so that the apparatus no longer provides you with adequate protection.

6. Oxygen deficiency in a mine can result from:

7. Exposure to low levels of carbon monoxide (0.15 to 0.20 percent) is not dangerous.

8. High nitrogen dioxide readings could indicate:

9. Which of the following applies to hydrogen sulfide?

10. Methane will be found only in bituminous coal mines or near oil/gas wells that penetrate metal/nonmetal mines.