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How many valence electrons does radium have?

Radium is an alkali earth metal that is very radioactive. Discovered by the French scientist couple Marie and Pierre Curie, radium's dangerous radioactivity eventually led to Marie's premature death. As a result, radium is rarely produced and barely worked with in chemical laboratories. Its instability renders it too dangerous for consumer use, even though it was originally used in luminescent paints and cancer treatments.

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Who is Kurt Alder?

Alder, who was born in Prussia (now Poland) in 1902, was one of the world's most-accomplished chemists during his lifetime. Alder's research has been lauded in about 150 scientific papers. By the time of his death in 1958, Alder had received many distinguished recognitions for his scientific contributions. In 1938, he became a member of the Imperial Leopold-Karol-German Academy of Natural Philosophers. He also received an honorary doctorate from the University of Salamanca in 1954.

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How do avalanches happen?

When snow falls on a mountain, each part of the slope collects some of the snowfall, allowing the excess to slide or fall down to lower levels safely. Avalanches can occur when large amounts of snow build up in unstable areas of the mountainside either due to heavy snowfall or temperature conditions. For instance, cold temperatures may allow large snowdrifts to build up and freeze together, only to present an avalanche danger when temperatures rise and the mass begins to melt and fracture.\nWhen a slope holds an unstable mass of snow, it is prone to avalanches. Loud sounds and vibrations can t..

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What two colors mix to make purple?

In theory, a pure blue color mixed with a pure red should give a proper hue of purple. However, many paint colors contain different mixtures of pigments. To avoid a muddy purple, it is wise to find a blue color that does not contain any of the added pigments red, yellow or green. Similarly, the red paint color should not have yellow pigment.Besides red and blue, the other primary color is yellow. These are colors that cannot be made by mixing other colors together. Secondary colors are colors made by mixing two primary colors.

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What is a second-class lever?

First-class levers are those which have the fulcrum placed between the load and the effort. Examples of first-class levers are the seesaw and crowbar. On a seesaw, for example, the person on the higher end of the plank acts as the effort, applying a downward force to the end of the lever. The person on the other end is the load, and the point at which the plank pivots is the fulcrum.\nOhio University lists the wheelbarrow as an example of a second-class lever. The effort is applied to the handles, the axle of the wheel acts as the fulcrum or pivot point, and the load is found in the middle.\nT..

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Where are complementary colors located on a color chart?

A color wheel is a color chart in a round shape, which shows colors and their relationships. A color wheel usually consists of 12 colors: the three primary colors red, yellow and blue; the three secondary colors green, orange and purple; and the six tertiary colors red-purple, red-orange, yellow-green, yellow-orange, blue-green and blue-purple. All secondary colors are a mix of two primary colors, and all tertiary colors are a mix of one primary and one secondary color.

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Why are atoms invisible to visible light?

In order for an object to be visible, light must be able to bounce off its surface. Objects smaller than the natural wavelength of the light being used to scan them are invisible, as they allow the larger waves of low-frequency light to pass through them without bouncing back to an observer. Visible light has a wavelength of between 380 nanometers for violet and 740 nanometers for red. This means that the smallest object that can be perceived in red light must be larger than 740 nanometers across and that the smallest object that can be seen in violet must be no less than 380 nanometers across..

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What conditions cause iron nails to rust faster?

Iron rust is flaky, porous and friable, providing no protection to subsurface layers against rusting. Rusting can occur on pure iron and iron alloys, such as steel. Steel rust can be dangerous because it may eat away at specific regions of the exposed bulk that are electrochemically favorable for rusting. This can lead to unanticipated failure of steel parts when the localized rusting is not counteracted in time. Pure iron immersed in a corrosive environment rusts uniformly all over its surface, making visual inspection and corrosion rate calculations easier. Anaerobic rusting can occur in the..

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How does matter cycle through an ecosystem?

Since carbon atoms are the backbone of cellular formation, the most important biogeochemical cycle is the carbon cycle. There are six major steps in the carbon cycle.PhotosynthesisPlants build carbohydrates by taking in carbon dioxide from the atmosphere.Carbon moves through the food chainAs organisms eat other organisms, carbon moves up the food chain. Molecules in the food that contain carbon transform into the organic molecules that make up the living body.Carbon moves back to the environmentOrganisms use food molecules, containing carbon, as a form of energy. The process of cellular respir..

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What are some plants that are toxic to humans?

Castor beans and rosary peas are among the most toxic plants. Consuming even one castor bean or rosary pea can cause death. Rhubarb leaves are toxic when consumed, and many common flowers, such as chrysanthemums, daffodils and daisies, contain toxins.\nSome flowers, such as aconite and monkshood, are very toxic and can cause serious symptoms if any part of the flower is consumed. Consuming the foliage or seeds of the yew tree can cause sudden death, and all parts of the lantana are toxic when consumed. Some plants, such as chamomile, croton and balsam fir, cause skin irritation or rash.\nMayap..

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