Answer:
Helium
It will not easily react with other elements as it is a noble gas. it has complete octate .the reactivity of an element depends on its outer most electron, ( or valency of it) but in helium there is no electron left to react.
Answer:
In the given case, the brain of the alien would be showing an enlarged region with surface grooves and folds. It is nothing but the cerebral cortex and mainly the neocortex. As the name suggests that it is the latest addition to the brain and is regarded to be originated by the process of evolution.
It is the main region of extraordinary cognitive tendencies like reasoning, thinking, analysis, and other things. As mentioned in the question, that alien is trained like astronauts on the Earth, thus, this neocortex would be certainly found in the brain of the alien.
The same amino acid in organisms
The answer is B: a food web is made up of two or more interconnected food chains