B is the correct answer since both Gondwanaland and Laurasia both technically came after pangaea
<span>2 Na + CaF</span>₂<span> = 2 NaF + Ca
is an example of a </span>single- replacement
answer D
hope this helps!
Answer: <u>Hydrogen.</u>
Explanation: <u>One problem with fuel-cell cars is that hydrogen gas is not readily available in pure form.</u> Fuel cell vehicles use hydrogen gas to power an electric motor. Unlike conventional vehicles which run on gasoline or diesel, fuel cell cars and trucks combine hydrogen and oxygen to produce electricity, which runs a motor. Hope this helps ^-^.
The o-xylene, m-xylene, and p-Xylene are constitutional isomers. The correct option is D.
<h3>What are isomers?</h3>
Isomers are the elements or polyatomic elements that have similar molecular formula.
All options are attached here:
A.optical isomers
B.structural isomers
C.geometric isomers
D.constitutional isomers
Thus, the correct option is D.constitutional isomers.
Learn more about isomers
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