An ocean trench .
a. marks the upwelling of mantle material.
b. is the site of submarine volcanoes.
c. occurs where a plate in moving down.
d. started breakup to the single southern continent.
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How are isotopes of the same chemical element alike? how are they different?

What metric units would you use to measure the thickness of a key

Inside a flashbulb, oxygen surrounds a thin coil of magnesium. when the flashbulb is set off, a chemical reaction takes place in which magnesium combines with oxygen to form magnesium oxide. which of the chemical equations matches the reaction above? a. mg + o2 mgo2 + energy b. 2mg + o mg2o + energy c. 2mg + o2 2mgo + energy d. mg + o mgo + energy