Leaving a beaker of water open to the air until it is empty is a phisscal or chemical change ?

Question

Heating a piece of calcium carbonate is a physical or chemical change ?

Adding copper sulphate to crystal water is it a chemical or physical change?

How to seeds disperse and the reasom ?

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the degree of exactness of a mesurement is accuracy

Since this is not my area of expertise, I searched Google under the key words "physical chemical change" to get these possible sources:

http://www.chem4kids.com/files/matter_chemphys.html
http://www.fordhamprep.org/gcurran/sho/sho/lessons/lesson15.htm
http://www.quia.com/quiz/303980.html
(Broken Link Removed)

For your last question, you can use the key words, "seeds disperse." As a reason, imagine that you, your children, your grandchildren and so on lived in the same house. Generalize this to seeds.

In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.

I hope this helps. Thanks for asking.