Science Q & A

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TEXTTEXT/me
Why do leaves change color in the falls?

Tree leaves contains a chemical called chlorophyll, which makes them look green in spring and summer. Chlorophyll helps capture light energy from the sun and change it to a chemical form. loke sugar, as food for the tree. The leaves also contain yellow and orange carotenoids [the substance that makes carrots orange], but the green chlorophyll in spring and summer masks those other colors. In the fall, as days get shorter and colder, the chlorophyll breaks down and the yellow and orange show up. If the temperature falls below 45 degrees at night, sugar made during the day gets trapped in the leaves. This is what makes suger maple leaves look red.

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Why does shaking a can of soda make it spray all over?

A can of soda contains carbon dioxide gas under pressure. The pressure makes it dissolve in the soda. Molecules in a liquid have a strong attraction for each other called surface tension. it take energy to separate them, so it is hard for the carbon dioxide inside the can to form bubbles. once the bubble is formed, it takes less energy for the gas molecules to join the existing bubble.
When you open a soda can, the gas escapes slowly and the soda takes a long time to go flat, But if you shake the can first, the little bit of gas above the soda seeps into the liquid as small bubbles. this gives the gas many starting points to get out-- in a hurry./color]