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Questions in chemistry

[Terjawab] What is "plastic" rock and how does it move?

[Terjawab] Which processes of the water cycle occur by releasing energy?

[Terjawab] If it takes one second to count two rice grains, calculate the time in years required to count a mole of rice grains.

[Terjawab] Lee conducts an experiment to see if mass is conserved when a piece of charcoal is burned for 5.0 minutes. He measures the mass of the charcoal before lighting it with a match. At the end of 5.0 minutes, Lee puts out the fire by suffocating it. After the charcoal has cooled, he measures its mass again. His data are below: | Initial Mass | Final Mass | |--------------|------------| | 0.415 g | 0.289 g | Charlene tries to repeat Lee's experiment by using a different piece of charcoal. But she burns the charcoal for just 3.0 minutes and collects all of the gas and dust released by the burning charcoal. She then weighs the total mass of these objects. Her results are below: | Initial Mass | Final Mass | |--------------|------------| | 0.498 g | 0.498 g | Charlene's experimental results indicate that mass was conserved. Why do Lee's results indicate that mass was not conserved? A. He burned the charcoal for a longer period of time than Charlene did. B. He did not collect the gas and dust released by the burning charcoal. C. He forgot to measure the mass of the charcoal while it was still burning. D. Mass is not conserved when an object undergoes a chemical change.

[Terjawab] True or False? An element's reactivity is determined by the number of protons found in an atom of the element.

[Terjawab] What type of reaction is: \[ \text{FeS} + 2 \text{HCl} \rightarrow \text{FeCl}_2 + \text{H}_2\text{S} \]

[Terjawab] A chloride dissolves in water to form a colored solution. The chloride could be: 1. HCl 2. KCl 3. CaClâ‚‚ 4. NiClâ‚‚

[Terjawab] What information about an atom's properties can you read from the periodic table?

[Terjawab] Suppose you stir a little baking soda into water until the water looks clear again. How could you prove to someone that the clear material is a solution, not a compound?

[Terjawab] On the Earth's surface, transported materials are more common than residual materials. This condition is mainly the result of: