Question

what group of archaea uses energy from h2; produces methane as waste; poisoned by o2. extreme halophiles methanogens nonextreme archaea extreme thermophiles

Explanation:

Methanogens are a group of Archaea that use hydrogen (\(H_2\)) as an energy source. They produce methane (\(CH_4\)) as a waste product. Methanogens are also poisoned by oxygen (\(O_2\)), meaning they are obligate anaerobes. Extreme halophiles thrive in high - salt environments, non - extreme Archaea do not have such specific and unique metabolic characteristics as described, and extreme thermophiles thrive in high - temperature environments.

Answer:

Methanogens