The ocean is salty because rivers and rain dissolve minerals from rocks and soil, carrying them into the sea over millions of years. These minerals, primarily salt, accumulate in the ocean and cannot easily escape, making the water increasingly salty.

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Onions make you cry because they release a chemical gas called syn-propanethial-S-oxide when their cells are cut open. This gas irritates your eyes and triggers tear production as a protective response.

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Spicy food tastes hot because capsaicin, a compound in chili peppers, activates pain receptors in your mouth that normally respond to heat. Your brain interprets these pain signals as a burning or hot sensation, even though the food isn't actually hot.

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Bread dough rises because yeast cells produce carbon dioxide gas as they eat sugar and multiply. This gas creates tiny bubbles throughout the dough, making it expand and become lighter and fluffier.

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Paraloid B-72 is an acrylic resin commonly used in conservation because it is reversible, transparent, and resistant to yellowing over time. It forms a protective coating that can be removed without damaging the original object.

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