MCAT General Chemistry Question 251: Answer and Explanation

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Question: 251

5. Particles with opposite charges attract one another and particles with like charges repel. How can protons, which are positively charged, coexist in the nucleus?

  • A. The neutrons in the nucleus prevent the protons from touching one another.
  • B. The nuclear force is stronger than the repulsive forces between protons.
  • C. Hadrons do not experience forces with one another.
  • D. The surrounding cloud of electrons generates an opposing force.

Correct Answer: B

Explanation:

B The passage describes the nuclear force as being responsible for holding the nucleons in the nucleus together and that it "overcomes other forces that may be present." Therefore, choice B is the best answer because it explains how protons are held together in close proximity despite having the same charge. The passage provides us with no indication that neutrons are preventing protons from touching one another, and particles need not physically touch in order to experience repulsion, eliminating choice A. The passage does describe how hadrons are held together by the strong force, eliminating choice C. The electron cloud surrounding the nucleus experiences an attractive force between the positive protons and the negative electrons. It is unlikely that this could generate an opposing force to prevent the repulsion of like-charged nucleons, eliminating choice D.

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