What is the total number of atoms reprsented in the formula cuso4?

If two atoms are bonded to a central atom with no lone pairs,how will they be arranged

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

How do you know when a chemical reaction has occurred