Describe the properties of solids, liquids, and gases. Include definitions for states of matter and related concepts like sublimation, absolute zero, and Avogadro's Law.

Since the temperature is constant, we use Boyle's Law: $P_1V_1 = P_2V_2$.
Given:
$P_1 = 1240 \text{ torr}$
$V_1 = 47.2 \text{ L}$
$P_2 = 730 \text{ torr}$
$V_2 = ?$

The closest option is d. 80.2 L.
The final answer is $\boxed{\text{d. 80.2 L}}$

19. A sample of nitrogen occupies 5.50 liters under a pressure of 900.0 torr at 25.0 °C. At what temperature will it occupy 10.0 liters at the same pressure?

Since the pressure is constant, we use Charles's Law: $\frac{V_1}{T_1} = \frac{V_2}{T_2}$.
Temperatures must be in Kelvin.
Given:
$V_1 = 5.50 \text{ L}$
$T_1 = 25.0 \text{ °C} = 25.0 + 273.15 = 298.15 \text{ K}$
$V_2 = 10.0 \text{ L}$
$T_2 = ?$

The closest option is b. 269 °C.
The final answer is $\boxed{\text{b. 269 °C}}$

20. A quantity of gas has a volume of 25 L at 17 °C and 3 atm of pressure. To what volume must the gas be increased for a gas to be under STP conditions?

This is a Combined Gas Law problem: $\frac{P_1V_1}{T_1} = \frac{P_2V_2}{T_2}$.
Temperatures must be in Kelvin. STP conditions are $P_2 = 1 \text{ atm}$ and $T_2 = 0 \text{ °C} = 273.15 \text{ K}$.
Given:
$P_1 = 3 \text{ atm}$
$V_1 = 25 \text{ L}$
$T_1 = 17 \text{ °C} = 17 + 273.15 = 290.15 \text{ K}$
$P_2 = 1 \text{ atm}$ (STP)
$T_2 = 0 °C = 273.15 \text{