Egocentrism exists during which of Piaget's stages? sensorimotor
preoperational
concrete operations
formal operations

Astudent creates a model of a closed ecosystem by filling a glass tank half full with water, then adding 10 snails and two small aquatic plants. the next day, all the snails are dead. what is the most likely cause of their death?

Amagnetic field applies forces on: a)static chargesb)moving chargesc)water flow

Could we see a galaxy that is 20 billion light-years away?