You could swallow a capsule of germanium without ill effects. But, if a proton were added to each of the germanium nuclei, you would not want to swallow the capsule. Why?

Which are older, the atoms in the body of an elderly person, or those in the body of a baby?

Why is it easier for the body to excrete a polar molecule than to excrete a nonpolar molecule? What chemistry does the body use to get rid of molecules it no longer needs?

How might you tell whether or not your toothpaste contained calcium carbonate, ${CaCO}_3$, or perhaps baking soda, ${NaHCO}_3$, without looking at the ingredients label?

When a container of gas is heated, would you expect its molecules to speed up, slow down, or be unaffected?

Fish don't live very long in water that has been boiled and brought back to room temperature. Provide an explanation for this fact.

The half-life of carbon-14 is 5730 years. What is the age of a fossil containing 1/16 the amount of carbon-14 of living organisms? Explain your reasoning.

Rank these noble-gas atoms by their number of filled shells, from least to most: (a) argon, (b) radon, $(c)$ helium, (d) neon.

How does the second law of thermodynamics relate to the direction of heat flow?

A railroad diesel engine weighs four times as much as a freight car. The diesel engine coasts at 5 km/h into the freight car that is initially at rest. After they couple together, show that the two coast at 4 km/h.

A railroad diesel engine weighs four times as much as a freight car. If the diesel engine coasts at 5 km/h into a freight car that is at rest, how fast do the two coast after they couple?

A business jet of mass 30,000 kg takes off when the thrust for each of two engines is 30,000 N. Show that its acceleration is 2 m/s2.

While riding on a carnival Ferris wheel, Sam Nasty horses around and climbs out of his chair and along the spoke so that he is halfway to the axis. How does his rotational speed compare with that of his friends who remain in the chair? How does his tangential speed compare? Why are your answers different?

Rank the following in order of increasing volume: (a) bacterium, (b) virus, (c) water molecule.