Answers:Â
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1) Which increase the rate of a chemical reaction?
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Answer: Â [A]: Â a catalyst .
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Note: Â A catalyst increases the rate of chemical reaction without altering the chemical reaction itself.
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2) How does a catalyst appear in a chemical equation?
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Answer: Â [A]: it uses does usually appear in an equation.
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Note:Â Since a catalyst is not used up or changed during the chemical reaction, catalysts usually do not appear in a chemical equation.
  {Occasionally, the catalyst is denoted above the "arrow" in the chemical equation, for emphasis that the catalyst was used."}.
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