Strong epidemiologic evidence that cigarette smoking was a major case of heart disease existed long before there was any biological evidence.

a. true
b. false


a. true

Physics & Space Science

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Deuterium oxide, ImageO, and water, ImageO, have the same chemical structure and differ only in that ImageO possesses the deuterium isotope of hydrogen, whereas water possesses the protium isotope

Deuterium oxide, also known as "heavy water," is 11 percent heavier than water. Might you expect its boiling temperature also to be about 11 percent greater? Why or why not? A) The mass of the molecules has a far greater influence on the boiling temperature of the substance than does the polarity of the molecules, so ImageO boils at a higher temperature. B) Since they have the same chemical structures, there is a similar molecular attraction between the molecules, so their boiling temperatures are similar. C) Since deuterium is radioactive, it breaks down more easily, so it has a lower boiling temperature than water. D) Since boiling temperature is a measure of the speed of a molecule, the heavier molecules move slower and thus have a higher boiling temperature.

Physics & Space Science

What is the evidence for an accelerating universe?

A) White-dwarf supernovae are the same brightness regardless of redshift. B) White-dwarf supernovae are slightly brighter than expected for a coasting universe. C) White-dwarf supernovae are slightly dimmer than expected for a coasting universe. D) The Andromeda Galaxy is moving away from the Milky Way at an ever-increasing speed. E) There is far more dark matter than visible matter in the universe.

Physics & Space Science

The spectra of molecules are more complex because molecules can vibrate and ________ instead of just exhibiting electronic transitions like atoms

Fill in the blank(s) with correct word

Physics & Space Science

An object of mass m is attached to a horizontal spring, stretched to a displacement A from equilibrium and released, undergoing harmonic oscillations on a frictionless surface. The experiment is then repeated with a mass of 4m. Compared to the original total mechanical energy, the subsequent total mechanical energy of the object with mass 4m is

1.greater. 2.less. 3.equal.

Physics & Space Science