*Question*
Answer the following question given this paragraph: When we run a reaction to produce a gas, we expect it to rise into the air. Many students have done experiments where gases such as hydrogen are formed. The gas can be trapped in a test tube held upside-down over the reaction. Carbon dioxide, on the other hand, sinks when it is released. Carbon dioxide has a density greater that air, so it will not rise like these other gases would. Q: Carbon dioxide does not rise like other gases because it has a density greater than what? Choices: - gravity - light - water - air A:
**Answer**
air

*Question*
Answer the following question given this paragraph: Electrons were the first particles with mass to be directly confirmed to have the wavelength proposed by de Broglie. Subsequently, protons, helium nuclei, neutrons, and many others have been observed to exhibit interference when they interact with objects having sizes similar to their de Broglie wavelength. The de Broglie wavelength for massless particles was well established in the 1920s for photons, and it has since been observed that all massless particles have a de Broglie wavelength = h / p. The wave nature of all particles is a universal characteristic of nature. We shall see in following sections that implications of the de Broglie wavelength include the quantization of energy in atoms and molecules, and an alteration of our basic view of nature on the microscopic scale. The next section, for example, shows that there are limits to the precision with which we may make predictions, regardless of how hard we try. There are even limits to the precision with which we may measure an object's location or energy. Making Connections: A Submicroscopic Diffraction Grating The wave nature of matter allows it to exhibit all the characteristics of other, more familiar, waves. Diffraction gratings, for example, produce diffraction patterns for light that depend on grating spacing and the wavelength of the light. This effect, as with most wave phenomena, is most pronounced when the wave interacts with objects having a size similar to its wavelength. For gratings, this is the spacing between multiple slits. ) When electrons interact with a system having a spacing similar to the electron wavelength, they show the same types of interference patterns as light does for diffraction gratings, as shown at top left in Figure 29.24. Atoms are spaced at regular intervals in a crystal as parallel planes, as shown in the bottom part of Figure 29.24. The spacings between these planes act like the openings in a diffraction grating. At certain incident angles, the paths of electrons scattering from successive planes differ by one... Q: What were the first particles with mass to be directly confirmed to have the wavelength proposed by de broglie? Choices: - negatrons - protons - ions - electrons A:
**Answer**
electrons

*Question*
Answer the following question given this paragraph: Humans have been making and using magnifying lenses for thousands of years. The first telescope was built by Galileo in 1608. His telescope used two lenses to make distant objects appear both nearer and larger. Q: Who built the first telescope? Choices: - newton - brahe - copernicus - galileo A:
**Answer**
galileo

*Question*
Answer the following question given this paragraph: Hearing is the ability to sense sound energy and perceive sound. The ear is the organ that senses sound and allows us to hear. Damage to structures of the ear may cause hearing loss. Total hearing loss is called deafness. Q: What do you call the ability to sense sound energy and perceive sound? Choices: - tuning - sensory deprivation - echolocation - hearing A:
**Answer**
hearing