conversión del vapor de agua en lluvia, es un cambio físico o cambio químico y por qué / conversion of water vapor into rain, is it a physical change or chemical change and why​

An atom of which element reacts with an atom of hydrogen to form a bond with the greatest degree of polarity ?

All forces cause motion? true or false

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