Answer: 2. cannot be an element.
Explanation:
Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Copper 
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: methane 

Thus as it can be decomposed into its constituent elements, it is a compound.
Mixture is a substance which has two or more components which do not combine chemically and do not have any fixed ratio in which they are present.
Thus methane cannot be an element.
Answer:
C
Explanation:
A - Crude oil is composed for hundreds of hydrocarbon, not less than ten.
B - Is formed in specific conditions of temperature and pressure
C - It's fractionated to form gasoline, lubricants, CH4, plastics and many other products made of hydrocarbon.
D - We have crude oil located more than 4000 yards below the surface in countries like Brazil
E - The crude oil is very thick and don't have an specific usage, so we need to refine it.
Answer:
The correct answer is skeleton equation.
Explanation:
In chemistry, the skeletal formula of a compound is an abbreviated representation of its molecular structure. Skeleton formulas are used because they clearly show complicated structures, they are fast and simple to draw.
All atoms that are not carbon or hydrogen are represented by their chemical symbol. The relative amounts of reagents and products are not indicated.
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Answer:
The formula of Quartz is SiO2. So, 1 mole of Quartz will have 2 moles of oxygen atoms, i.e. 2 x 6.022 x 10^23 atoms of oxygen. The molar mass of quartz is 60 g per mol. So, 60 g quartz means 1 mole quartz.
Explanation: