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Original Project
    Substances, Chemical Reactions, and Conservation of Matter
            Whenever atoms interact with each other, regardless of how they are arranged or rearranged, the total mass stays…

Item SC102002: The number of each kind of atom stays the same during a chemical reaction. (This item uses circles to represent atoms.)

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The diagram below shows molecules before they react in a chemical reaction. Atoms are represented by circles, and molecules are represented by circles that are connected to each other. The different colored circles represent different kinds of atoms.

Which of the following diagrams could represent the molecules that result from the chemical reaction and why?

  1. Because there were 6 atoms before the reaction and 6 atoms after the reaction.
  2. Because there were 2 kinds of molecules before the reaction and 2 kinds of molecules after the reaction.
  3. Because there were 4 white atoms and 2 gray atoms before the reaction and 4 white atoms and 2 gray atoms after the reaction.
  4. Because there were 3 molecules before the reaction and 3 molecules after the reaction.
Distribution of responses
Answer Choice
Overall
Grades
Gender
Primary Language
 
n = 2717		 6–8
n = 1603		 9–12
n = 1094		 Male
n = 1295		 Female
n = 1366		 English
n = 2387		 Other
n = 261
A.
Because there were 6 atoms before the reaction and 6 atoms after the reaction.
18% 19% 17% 18% 18% 18% 20%
B.
Because there were 2 kinds of molecules before the reaction and 2 kinds of molecules after the reaction.
16% 17% 15% 17% 15% 16% 18%
C.
Because there were 4 white atoms and 2 gray atoms before the reaction and 4 white atoms and 2 gray atoms after the reaction.
55% 52% 58% 54% 55% 55% 47%
D.
Because there were 3 molecules before the reaction and 3 molecules after the reaction.
11% 12% 11% 11% 12% 11% 15%