Question

Nuclear fusion is a process whereby the nuclei of atoms are jouned, or "tused," and in which energy is released. One of the by-products of fusion is helium \(-4\) gas. A recent fusion experiment was conducted using "heavy" water contained in a sealed flask. The flask was, in turn, contained in an air- filled chamber designed to eliminate extraneous vibration. After the experiment, a measurable amount of helium-4 gas was found in the air of the chamber. The experimenters cited this evidence in support of their conclusion that fusion had been achieved. Which one of the following, if true, would cast doubt on the experimenters' conclusion? (A) Helium-4 was not the only gas found in the experiment chamber. (B) When fusion is achieved, it normally produces several by-products, including tritium and gamma rays. (C) The amount of helium-4 found in the chamber's air did not exceed the amount of helium-4 that is found in ordinary air. (D) Helium-4 gas rapidly breaks down, forming ordinary helium gas after a few hours. (E) Nuclear fusion reactions are characterized by the release of large amounts of heat.

Short answer

Option (C) casts doubt on the experimenters' conclusion.

Step-by-step solution

Identify the experiment's goal

The goal of the experiment was to achieve nuclear fusion, evidenced by the presence of helium-4 gas as a by-product in the air of the chamber that would not normally exist unless fusion occurred.

Determine what finding helium-4 indicates

Finding helium-4 gas in the chamber is used by the experimenters to support their claim that fusion occurred during the experiment.

Evaluate each option for its potential to cast doubt

Evaluate the given options to see which one suggests that the presence of helium-4 gas might not be due to nuclear fusion.

Analyze Option (C)

Option (C) suggests that the amount of helium-4 found did not exceed the typical amount present in ordinary air. This implies that the helium-4 detected might not be unique to the experiment and thus, not necessarily evidence of fusion.

Conclusion on casting doubt

Option (C) effectively casts doubt on the claim that fusion was achieved, by suggesting that the presence of helium-4 may not have originated from the experiment due to its typical presence in ordinary air.

Key concepts

Nuclear Fusion

Nuclear fusion is a fascinating process whereby two atomic nuclei combine to form a heavier nucleus, releasing a massive amount of energy. This phenomenon primarily occurs in the cores of stars, where enormous pressure and temperature conditions enable fusion. On Earth, achieving controlled nuclear fusion could offer a nearly limitless and clean energy source, as it uses isotopes of hydrogen such as deuterium and tritium to generate energy.
The fusion process releases energy because the mass of the resulting atom is slightly less than the sum of the original nuclei. This lost mass is converted into energy according to Einstein's famous equation, ([E=mc^2](https://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence)), illustrating the efficient energy potential of fusion. Understanding this process aids in developing new energy technologies, potentially revolutionizing how humanity produces and consumes energy. Exploring the depths of nuclear processes not only strengthens scientific knowledge but also enhances our capability to harness them for practical uses.

Scientific Experimentation

Scientific experimentation serves as the backbone for testing hypotheses, understanding phenomena, and establishing scientific facts. It involves a systematic process: framing research questions, designing experiments, collecting data, and analyzing results. Each step is critical. In a nuclear fusion experiment, accurate observations lead to evidence-based conclusions.
Experiments are meticulously planned to control variables, eliminate biases, and achieve reliable results. In this context, factors such as ensuring no contamination of helium-4 from external sources and maintaining stable conditions in the experimentation chamber are paramount. Furthermore, successful experimentation requires careful documentation and repeatability, ensuring that findings are reliable and verifiable by independent researchers. An experiment's integrity relies on its design and execution, profoundly affecting the credibility of its conclusions.

Critical Thinking

Critical thinking plays a vital role in interpreting experimental results. It demands more than a surface-level acceptance of outcomes, requiring deep analysis and questioning of findings. By engaging critical thinking, scientists and students alike can challenge assumptions and evaluate whether the presented evidence truly supports the conclusions drawn.
For example, in the nuclear fusion experiment, individuals must scrutinize whether the detected helium-4 gas genuinely indicates fusion or if alternative explanations exist. Critical thinkers look beyond the obvious, asking essential questions like: Does the amount of helium-4 align with background atmospheric levels? Are there other potential sources for the helium-4? Critical thinking encourages diverse perspectives, leading to more nuanced understanding and more robust scientific inquiry. Hence, fostering such skills empowers learners to approach problems holistically and with open-minded skepticism.

Evidence Evaluation

Evaluating evidence involves assessing the strength and relevance of data to support a scientific claim. In scientific inquiries, such as nuclear fusion experiments, it is crucial to determine whether evidence like the presence of helium-4 truly substantiates the experimenters' claims. This evaluation process requires an objective analysis of the data quality and context.
Key steps in evidence evaluation include: - Ensuring data accuracy - Comparing experimental results with expected benchmarks - Considering potential sources of error or bias - Evaluating the representativeness of the data gathered Moreover, real-world applications demand that the given evidence must not only be consistent but also sufficient to confirm the hypothesis. For instance, if the helium-4 levels do not surpass typical atmospheric amounts, this could weaken the claim that nuclear fusion occurred. Thus, rigorous evidence evaluation is essential for advancing scientific knowledge and validating experimental findings.