Which of the following is a clue of a chemical change?

A. iron changes color when heated

B. gas bubbles form in boiling water

C. balls of wax form when melted wax is poured into ice water

D. a gas forms when vinegar and baking soda are mixed

A student was visiting a friend at her home. Her friend owned two cats. After playing with the cats for a while, the student began to sneeze. Her nose began to run and her eyes became red, watery, and itchy. It also became hard for her to breathe.

Variations can be A. only negative B. negative, positive, or neutral C. only neutral D. only positive

What species in Alaska has become vulnerable that the local people depend on?

What was Anton van leeuwenhoek's contribution in the devolopment of cell theory?

Chromosomes move to the middle of the spindle during what phase

From the producer level to which level does energy flow directly? A. decomposer B. tertiary consumer C. secondary consumer D. primary consumer

What motion will result from two forces acting on an object : one forcee of 50 newtons to the east, the other a force of 30 newtons to the west? The object will-

Name the progression of coal types with increased heat and pressure from burial

Describe one benefit and one limitation of how the trichoplax can reproduce by simple division

The total economic value of an ecosystem: a. is composed of the direct values an ecosystem provides upon which a price can be placed, such as crops and medicinal plants. b. is the monetary value of all of the services an ecosystem provides.