Answer:
combination (synthesis) reaction
The alkali metals are so reactive that they are never found in nature in elemental form. Although some of their ores are abundant, isolating them from their ores is somewhat difficult. For these reasons, the group 1 elements were unknown until the early 19th century, when Sir Humphry Davy first prepared sodium (Na) and potassium (K) by passing an electric current through molten alkalis. (The ashes produced by the combustion of wood are largely composed of potassium and sodium carbonate.) Lithium (Li) was discovered 10 years later when the Swedish chemist Johan Arfwedson was studying the composition of a new Brazilian mineral. Cesium (Cs) and rubidium (Rb) were not discovered until the 1860s, when Robert Bunsen conducted a systematic search for new elements. Known to chemistry students as the inventor of the Bunsen burner, Bunsen’s spectroscopic studies of ores showed sky blue and deep red emission lines that he attributed to two new elements, Cs and Rb, respectively. Francium (Fr) is found in only trace amounts in nature, so our knowledge of its chemistry is limited. All the isotopes of Fr have very short half-lives, in contrast to the other elements in group 1.
C) convection cells (currents)
Explanation:
The movement of warmer cooler mantle rocks creating a circulation within the mantle is called a convection cell. These are the forces that drives the plate over asthenosphere.
- Convection is form of heat transfer predominant in liquids and gases.
- The mantle is molten and heated from heat within the core and the decay of radioactive bodies.
- Hot bodies are light and tend to be more buoyant. This causes warm mantle to rise to the surface.
- The cold part are denser and heavier, they sink in the mix.
- This creates pockets of circulation pattern within the mantle called convection cells.
Learn more:
Lithosphere brainly.com/question/9582362
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Answer: a communicable disease
Explanation: key word was transmitted and it was transmitted from a INFECTED living thing and then transmitted to another living thing
The answer is 600N because if its 600 and 0 its still going to be 600