Answer:
a: chemical change because the change cannot be reversed.
b: physical change because the action can be reversed.
c: chemical change.
d:chemical change.
any change that cannot be reversed is a chemical change and any change that can be reversed is a physical change.
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Explanation:
In laboratory, carbon dioxide is not obtained from the air, carbon dioxide is prepared from carbonates by adding acids to the carbonates. In this experiment carbon dioxide is prepared by the reaction of marble with hydrochloric acid.
Answer: In octet state.
Explanation: For noble gases they are stable in state since their outer shell contain fully occupied having 8 electrons.
A because if you multiple it, you will be moving the decimal one time
