A neutron strikes an atom of uranium-235 to start a fission reaction. A student expresses this situation as 0/1n+235/92U. Which statement describes why the expression is incorrect?
• The atomic number for uranium-235 is in the wrong location
• A neutron should be expressed as 1/1 H, not 0/1H.
• The mass number for uranium-235 is in the wrong location
• A neutron should be expressed as 1/0n, not 0/1n.
The correct statement that describes why the expression is incorrect is:
• A neutron should be expressed as 1/0n, not 0/1n.
The correct statement is: A neutron should be expressed as 1/0n, not 0/1n.
The correct answer is "The atomic number for uranium-235 is in the wrong location."
In the expression given by the student (0/1n + 235/92U), the atomic number (92) for uranium-235 is positioned as the numerator, while it should be placed as the subscript at the bottom left of the element's symbol. The numerator represents the mass number, which indicates the total number of protons and neutrons in the atom. The denominator represents the atomic number, which signifies the number of protons.
Therefore, the correct expression for uranium-235 should be written as 235/92U.