Questão FC170801
Text 1A1-I Hydrogen is viewed as a promising alternative to fossil fuel, but the methods used to make it either generate too much carbon dioxide or are too expensive. Rice Universi
Semântica e Significado de Vocábulos (Semantics)
CEBRASPE (CESPE) · 2023
Hydrogen is viewed as a promising alternative to fossil fuel, but the methods used to make it either generate too much carbon dioxide or are too expensive. Rice University researchers have found a way to harvest hydrogen from plastic waste using a low-emission method that could more than pay for itself.
By comparison, “green” hydrogen ⎯ produced using renewable energy sources to split water into its two component elements ⎯ costs roughly US$ 5 for just over two pounds. Though cheaper, most of the nearly 100 million tons of hydrogen used globally in 2022 was derived from fossil fuels, its production generating roughly 12 tons of carbon dioxide per ton of hydrogen.
The researchers exposed plastic waste samples to rapid flash Joule, bringing their temperature up to 3100 Kelvin. “We demonstrated that we are able to recover up to 68% of that atomic hydrogen as gas with a 94% purity,” Kevin Wyss said. “I hope that this work will allow for the production of clean hydrogen from waste plastics, possibly solving major environmental problems like plastic pollution and the greenhouse gas-intensive production of hydrogen by steam-methane reforming.”
Internet: <news.rice.edu> (adapted).
The sentence “‘green’ hydrogen ⎯ produced using renewable energy sources to split water into its two component elements ⎯ costs roughly US$ 5” could be correctly rewritten as the use of renewable energy sources to separate water into its two component elements produces ‘green’ hydrogen, which costs about US$ 5.
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Comentário: A reescrita da frase original está correta porque mantém o mesmo sentido. A nova estrutura enfatiza que a produção de ‘green’ hydrogen ocorre por meio do uso de fontes de energia renováveis para separar a água em seus dois elementos componentes, o que é uma descrição precisa do processo mencionado no texto. Além disso, a frase reescrita informa que essa forma de hidrogênio custa cerca de US$ 5, preservando a informação essencial da frase original, o que justifica a afirmação como "CERTO".
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