Answer:
element
Explanation:
we know that helium is a pure substance although helium atoms are sometimes mixed with their isotopes it is still the same element. since there is no other element combined with helium this makes it an element.
Answer: Option (D)
Explanation: Chemical weathering refers to the breakdown of minerals and forming new minerals due to the presence of chemical elements. For example, hydrolysis.
Due to the chemical weathering, initially, the minerals will get dissolved and are carried to the streams and oceans. After that, due to the saturation by water, the crystals will be precipitated out of that existing solution.
This crystals then sinks down to the bottom, forming sedimentary rocks.
Thus, the correct answer is option (D).
The classifying of organisms is called "Taxonomy" or the second option. Taxonomy mainly takes place with organisms although it could be used to classify anything. Taxonomy consists of a graph with eight categories all used to classify a living organism.
Hope this helps!
I say Answer choice A because it is a straight line and it hasn't gone under all those reactions yet.
