Air is $21 \%$ oxygen by volume. Oxygen has a density of $1.31 \mathrm{~g} / \mathrm{L}$. What is the volume, in liters, of a room that holds enough air to contain $55 \mathrm{~kg}$ of oxygen?

A glass of lukewarm milk is suggested for people who cannot sleep. Milk at $52^{\circ} \mathrm{C}$ can be characterized as lukewarm. What is the temperature of lukewarm milk in ${ }^{\circ} \mathrm{F}$ ? In K?

The volume of a sphere is $4 \pi r^3 / 3$, where $r$ is the radius. One student measured the radius to be $4.30 \mathrm{~cm}$. Another measured the radius to be $4.33 \mathrm{~cm}$. What is the difference in volume between the two measurements?

Calculate the following to the correct number of significant figures. Assume that all these numbers are measurements.

(a) $x=17.2+65.18-2.4$

(b) $x=13.0217 / 17.10$

(c) $x=(0.0061020)(2.0092)(1200.00)$

(d) $x=0.0034+\frac{\sqrt{(0.0034)^2+4(1.000)\left(6.3 \times 10^{-4}\right)}}{(2)(1.000)}$

Vinegar contains $5.00 \%$ acetic acid by mass and has a density of $1.01 \mathrm{~g} / \mathrm{mL}$. What mass (in grams) of acetic acid is present in $5.00 \mathrm{~L}$ of vinegar?

Wire is often sold in pound spools according to the wire gauge number. That number refers to the diameter of the wire. How many meters are in a 10-lb spool of 12-gauge aluminum wire? A 12-gauge wire has a diameter of $0.0808$ in. Aluminum has a density of $2.70 \mathrm{~g} / \mathrm{cm}^3 .\left(V=\pi r^2 \ell\right)$

How would you separate into its components (a) a homogeneous solution of table salt and water? (b) sand from gasoline? (c) carbon dioxide gas from butane gas?

How would you separate into its different components (a) a solution of acetone and water? (b) a mixture of aluminum powder and ethyl alcohol?

A waterbed filled with water has the dimensions $8.0 \mathrm{ft} \times 7.0 \mathrm{ft} \times 0.75 \mathrm{ft}$. Taking the density of water to be $1.00 \mathrm{~g} / \mathrm{cm}^3$, how many kilograms of water are required to fill the waterbed?

A solid with an irregular shape and a mass of $11.33 \mathrm{~g}$ is added to a graduated cylinder filled with water $(d=$ $1.00 \mathrm{~g} / \mathrm{mL}$ ) to the $35.0-\mathrm{mL}$ mark. After the solid sinks to the bottom, the water level is read to be at the $42.3-\mathrm{mL}$ mark. What is the density of the solid?

A metal slug weighing $25.17 \mathrm{~g}$ is added to a flask with a volume of $59.7 \mathrm{~mL}$. It is found that $43.7 \mathrm{~g}$ of methanol $(d=0.791 \mathrm{~g} / \mathrm{mL})$ must be added to the metal to fill the flask. What is the density of the metal?

The egg whites from four "large" eggs occupy a volume of $112 \mathrm{~mL}$. The mass of the egg whites from these four eggs is $1.20 \times 10^2 \mathrm{~g}$. What is the average density of an egg white from one "large" egg?

The cup is a measure of volume widely used in cookbooks. One cup is equivalent to $225 \mathrm{~mL}$. What is the density of clover honey (in grams per milliliter) if three quarters of a cup has a mass of $252 \mathrm{~g}$?

In the old pharmaceutical system of measurements, masses were expressed in grains. There are $5.760 \times 10^3$ grains in $1 \mathrm{lb}$. An old bottle of aspirin lists $5.000$ grains of active ingredient per tablet. How many milligrams of active ingredient are there in the same tablet?