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Questions in chemistry

[Done] If you forget to dry off a bread knife after washing it, and reddish-brown spots appear on it, would that be a physical or chemical change?

[Done] Are the following physical or chemical changes? 1. Lighting a match 2. Cooking waffles 3. Baking a cake

[Done] List four physical descriptions of elements: - Metal, non-metal, metalloid - Color - Texture - State (solid, liquid, gas) - Density - Melting point - Boiling point

[Done] Why do alkanes not appear in the periodic table?

[Done] Sally's teacher tells her to find the masses of a sugar cube and a glass of water. Sally finds the masses to be 10 g for the sugar cube and 100 g for the glass of water. Then, the teacher tells her to put the sugar cube into the water. Sally puts the cube into the glass of water and watches as it dissolves. Then, the teacher tells Sally to estimate the new mass of the glass of sugar-water. What should Sally guess as the new mass of the glass of sugar-water?

[Done] What are six abiotic factors from "Finding Nemo"?

[Done] Kia is doing an experiment in the science lab. She is given a beaker containing 100 g of liquid. The beaker has markings on the side for measuring volume, and the water initially comes up to the 100 mL mark. Kia accidentally places the liquid on a hot plate. By the time she realizes her mistake, half of the liquid has evaporated. Kia still needs 100 g of liquid for her experiment. To find out how much liquid she needs to replace, she must re-weigh her liquid. However, the balance she used is now broken. The teacher tells Kia that she can determine how much water is left by observing the volume. The water now comes up to the 50 mL mark. How much mass does Kia's remaining water have?

[Done] Copper is made of two isotopes. Copper-63 is 69.17% abundant and has a mass of 62.9296 amu. Copper-65 is 30.83% abundant and has a mass of 64.9278 amu. What is the weighted average mass of these two isotopes? Show your work.

[Done] What are the four attributes of a proper microscope drawing?

[Done] Antimony has 2 naturally occurring isotopes. The mass of antimony-121 is 120.904 amu and the mass of antimony-123 is 122.904 amu. Using the average atomic mass from the periodic table, find the abundance of each isotope. (Remember that the sum of the two abundances must be 100%. Show your work.)