Answer:
a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change
Answer:
(d) on the left side ,because it is a reactant.
Answer:
The variation of sunlight reaching Earth is one cause of ice ages. Over thousands of years, the amount of sunshine reaching Earth changes by quite a lot, particularly in the northern latitudes, the area near and around the North Pole.
Explanation:
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Answer:
Obsidian is not a mineral as the atoms or molecules in obsidian do not have a crystalline structure.
Explanation:
Obsidian originates naturally and is formed by igneous rock.
When felsic larva comes out from the volcano,it rapidly cools down and thus form obsidian.It is pure black in color but some times color differ due to presence of some impurities.
It is brittle,but hard.It is not a mineral and is called as mineraloids and is not found in crystalline form,.
The main constituent is SiO2.
It is found in the margin of rhyolitic lava.