If you were making observations of someone mixing two substances together, how would you know if a chemical reaction took place?

The response is the basis for vaccination. primary secondary tertiary none of the above

Which pair of sentences is describing the same velocity? a. a car is parked. a car is moving in circles. b. a bus drives 40 miles per hour north. a truck drives 50 miles per hour north. c. a boy walks east at 6 kilometers per hour. a girl walks west at the same speed as the boy. d. valerie rides her bike south at 8 kilometers per hour. owen jogs south at 8 kilometers per hour.

When wind creates a sand dune, the sheltered side of the dune is less steeply sloped than the windward side has the same incline as the windward side is more steeply sloped than the windward side