Which gas has the lowest specific gravity at 25° C and 760 mm Hg?

Which of the following occurs during the onset of inspiration?

A) Intrathoracic pressure increases and venous return to the heart is impeded. B) Intrathoracic pressure increases and venous return to the heart is facilitated. C) Intrathoracic pressure decreases and venous return to the heart is impeded. D) Intrathoracic pressure decreases and venous return to the heart is facilitated.

In areas without water mains and domestic fire hydrants, _______________ can provide a simple, cost-effective solution to the need for rapid access to water sources

a. the wet barrel concept b. the water shuttle concept c. the dry hydrant concept d. the large diameter hose concept