Answer:
13.C
14.B
15.C
16.Chemical element
Chemical Element are called substance or element that cannot be decomposed or broken down into simpler substances by ordinary chemical process.
Chemical elements are those elements which cannot be chemically broken down into simpler substances and are primary constituents of all matter. They are fundamental ingredients of all matter in existence which can be combined in reaction to create chemical substance each chemical element in the universe has unique properties that distinguish it from all of the Other chemical elements. For example hydrogen is an element.
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