QUES: The properties of matter depend on the types of atoms that matter is made of. Matter can exist in two forms. It can be a pure substance. This means it is not mixed with anything. It can also be a combination of different substances. This means it can be a mix of different types of atoms. You may recall that atoms differ based on the numbers of protons they contain. Some atoms contain only one proton such as Hydrogen. Other atoms contain many protons. There are many types of atoms. For example, Helium has two protons. An Oxygen atom has eight. Water is composed of a two types of atoms. Water is made of two Hydrogen atoms and one Oxygen atoms. There are only so many types of atoms. These atoms can be mixed into an almost limitless amount of substances. So what do we call a substance that has only a single type of atom?
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MY QUESTION: What is contained in water?

QUES: Density is also an important physical property of matter. The concept of density combines what we know about an objects mass and volume. Density reflects how closely packed the particles of matter are. When particles are packed together more tightly, matter is more dense. Differences in density of matter explain many phenomena. It explains why helium balloons rise. It explains why currents such as the Gulf Stream flow through the oceans. It explains why some things float in or sink. You can see this in action by pouring vegetable oil into water. You can see a colorful demonstration in this video.
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MY QUESTION: How can I observe the role density plays?

QUES: Grande dame of cooking still going strong at 90: Julia Child celebrates in San Francisco. How does it feel to turn 90 and have attained the status of an icon, a living legend? "It feels just like it felt before," Julia Child says with the throaty laugh familiar to millions who cut their culinary teeth on her "French Chef" television series. The show, along with her seminal book, "Mastering the Art of French Cooking" (1961), revolutionized the way America cooks and eats. While making light of the difference a day -- or another decade -- makes, Child intends to enjoy her birthday thoroughly. First, there will be all the public observances, including a sold-out dinner Thursday at San Francisco's tony Fifth Floor restaurant, which -- like dinners that night at 19 other venues across the country -- will benefit the scholarship fund of the International Association of Culinary Professionals (which Child co-founded). Friday to Sunday, the action moves to Napa, with both members-only and public events at COPIA: The American Center for Wine, Food and the Arts, of which she is an honorary board member. Aug. 15, her actual birthday, will see her in Maine at an annual gathering of nieces, nephews, their offspring and friends, who for many years have rolled a joined birthday celebration for several members of the group into a jolly reunion. The schedule Child and her assistant of 14 years, former pastry chef Stephanie Hersh, have laid out is not exactly a senior-citizen routine, even though Child has always been candid about her age and realistic in assessing her own capabilities. When the Pasadena native moved back to California from her long-time home in the Boston area last year, she also made the move from a condominium she and her late husband, Paul, had purchased many years ago to a progressive retirement home. She is in the most active of the four levels available, but should the need arise, she can move on to assisted living facilities within the same complex.
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MY QUESTION: Which show revolutionized the way America cooks and eats.

QUES: Dam Good Luck: From the beginning, Las Vegas was built to serve travelers. The railroad needed a way station, and Las Vegas was the place. Growth continued for ten years, and by 1915 the town had telephones, round-the-clock electricity, and a growing populationmany of whom worked in the railroad repair shop. But such heady progress would soon come to a halt. The growing competition in rail transport resulted in Union Pacific buying the Los AngelesSalt Lake line. Union Pacific then consolidated its operations, eliminating the Las Vegas repair facility. Additionally, Las Vegas had been made a part of Nevada's new Clark County in 1909, a year when the legislature also outlawed gambling. These unfortunate circumstances threatened to relegate Las Vegas to the status of a small desert community that could no longer support its 3000 residents. But the southwest's growing need for water, combined with Las Vegas's fortuitous proximity to the Colorado River, would give Las Vegas a second chance to achieve prosperity. Construction on Hoover Dam (originally Boulder Dam, subsequently renamed for the president who authorized the project) began in 1931 in a canyon 45 miles (72 km) southeast of Las Vegas. Providing an influx of $165 million to the southwestern economy, Hoover Dam played a major role in preventing Las Vegas from drying up, both financially and literally. Not only did it create jobs, but it also created Lake Mead, the massive reservoir that today provides water to all of southern Nevada. More Government Help: The construction of Hoover Dam did not single-handedly save Las Vegas, however. The state legislature helped as well, by legalizing gambling in 1931 and thus solidifying the future of the town, though legislators and residents could never have known this at the time. The hordes of people who attended Hoover Dam's 1935 dedication set the city's now-formidable public relations machine into action. They went to work on what has become one of the lengthiest citywide tourism campaigns ever attempted. It didn't take long for the city to establish itself as a wild-West town with an "anything goes" attitude. Vices outlawed or heavily controlled elsewhere were legal here, available any hour of any day (or night).
Do you have any questions?
MY QUESTION:
What man-made construction ended up creating jobs and also creating Lake Mead?