Before pavlov conditioned a dog to salivate in response to a tone, the tone was a(n):

Which of the following does not describe a physical property of iron? a iron is silvery-white or gray in color. b iron has a boiling point of about 3,000°c. c iron is a magnetic element . d iron and sulfur react to form iron sulfide.

Which of the following produces carbon dioxide? a. plants b. animals c. decomposers d. all of the above

The most famous fossil called archaeopteryx is which of the following? a dinosaur a fern a fish a bird