A helium balloon is used to lift a load of $110 \text{~N}$. The weight of the envelope of the balloon is $50.0 \text{~N}$ and the volume of the helium when the balloon is fully inflated is $32.0 \text{~m}^3$. The temperature of the air is $0^{\circ} \text{C}$ and the atmospheric pressure is $1.00 \text{~atm}$. The balloon is inflated with a sufficient amount of helium gas that the net upward force on the balloon and its load is $30.0$ N. Neglect any effects due to the changes of temperature as the altitude changes. $(a)$ How many moles of helium gas is contained in the balloon?

True or False: Airtight packages make the best containers for blood-containing evidence. $\rule{1cm}{1pt}$

A hot-air balloon is open at the bottom. The balloon, which has a volume of $446 \text{~m}^3$, is filled with air that has an average temperature of $100^{\circ} \text{C}$. The air outside the balloon has a temperature of $20.0^{\circ} \text{C}$ and a pressure of $1.00 \text{~atm}$. How large a payload (including the envelope of the balloon itself) can the balloon lift? Use $29.0 \text{~g/mol}$ for the molar mass of air. (Neglect the volume of both the payload and the envelope of the balloon.)

A scuba diver is $40 \text{~m}$ below the surface of a lake, where the temperature is $5.0^{\circ} \text{C}$. He releases an air bubble that has a volume of $15 \text{~cm}^3$. The bubble rises to the surface, where the temperature is $25^{\circ} \text{C}$. Assume that the air in the bubble is always in thermal equilibrium with the surrounding water, and assume that there is no exchange of molecules between the bubble and the surrounding water. What is the volume of the bubble right before it breaks the surface? Hint: Remember that the pressure also changes.

Calculate the mass density of air at a temperature of $24^{\circ} \mathrm{C}$ and a pressure of $1 \mathrm{~atm}\left(1.01 \times 10^5 \mathrm{~N} / \mathrm{m}^2\right)$ using the ideal-gas law. Air is roughly 74 percent $\mathrm{N}_2$ and 26 percent $\mathrm{O}_2$.

What is the output from the following code?

int max;
int min = 10;
max = 17 − 4 / 10;
max = max + 6;
min = max − min;
System.out.println(max * 2);
System.out.println(max + min);
System.out.println(max);
System.out.println(min);

After nitrogen $\left(\text{N}_2\right)$ and oxygen $\left(\text{O}_2\right)$, the most abundant molecule in Earth's atmosphere is water, $\text{H}_2 \text{O}$. However, the fraction of $\text{H}_2 \text{O}$ molecules in a given volume of air varies dramatically, from practically zero percent under the driest conditions to a high of $4$ percent where it is very humid. $(b)$ What is the difference in mass, at room temperature and atmospheric pressure, between a cubic meter of air with no water vapor molecules and a cubic meter of air in which 4 percent of the molecules are water vapor molecules?

After nitrogen $\left(\text{N}_2\right)$ and oxygen $\left(\text{O}_2\right)$, the most abundant molecule in Earth's atmosphere is water, $\text{H}_2 \text{O}$. However, the fraction of $\text{H}_2 \text{O}$ molecules in a given volume of air varies dramatically, from practically zero percent under the driest conditions to a high of $4$ percent where it is very humid. $(a)$ At a given temperature and pressure, would air be denser when its water vapor content is large or small?

An automobile tire is filled to a gauge pressure of $200 \text{kPa}$ when its temperature is $20^{\circ} \text{C}$. (Gauge pressure is the difference between the actual pressure and atmospheric pressure.) After the car has been driven at high speeds, the tire temperature increases to $50^{\circ} \text{C}$. $(b)$ Calculate the gauge pressure if the tire expands so the volume of the enclosed air increases by 10 percent.

An automobile tire is filled to a gauge pressure of $200 \text{kPa}$ when its temperature is $20^{\circ} \text{C}$. (Gauge pressure is the difference between the actual pressure and atmospheric pressure.) After the car has been driven at high speeds, the tire temperature increases to $50^{\circ} \text{C}$. $(a)$ Assuming that the volume of the tire does not change and that air behaves as an ideal gas, find the gauge pressure of the air in the tire.

Select the best answer. The scores on a statistics test had a mean of 81 and a standard deviation of 9. One student was absent on the test day, and his score wasn't included in the calculation. If his score of 84 was added to the distribution of scores, what would happen to the mean and standard deviation? (a) Mean will increase, and standard deviation will increase. (b) Mean will increase, and standard deviation will decrease. (c) Mean will increase, and standard deviation will stay the same. (d) Mean will decrease, and standard deviation will increase. (e) Mean will decrease, and standard deviation will decrease.

A container with a volume of $6.0 \mathrm{~L}$ holds $10 \mathrm{~g}$ of liquid helium. As the container warms to room temperature, what is the pressure exerted by the gas on its walls?

A closed container with a volume of $6.00 \text{~L}$ holds $10.0 \text{~g}$ of liquid helium at $25.0 \text{~K}$ and enough air to fill the rest of its volume at a pressure of $1.00 \text{~atm}$. The helium then evaporates and the container warms to room temperature $(293 \text{~K})$. What is the final pressure inside the container?

Imagine that $10.0 \text{~g}$ of liquid helium, initially at $4.20 \text{~K}$, evaporate into an empty balloon that is kept at $1.00$-atm pressure. What is the volume of the balloon at $(b)$ $293 \text{~K}$?