Which of the following describes a response to external stimuli?

a boy sneezes when exposed to cat dander

a girl eats food when she is hungry

a child becomes hyperactive due to a chemical imbalance

a person yawns when oxygen levels in the blood are low

Describe the particles of all three phases of matter in the root beer float. (how are the particles arranged and moving? )

Given sno2 + 2h2 - sn + 2h20 tin oxide reacts with hydrogen to produce tin and water. how many moles of sno2 are needed to produce 500.0 grams of sn?

Which of the following statements is true about energy quantization at the atomic level? electrons in the outermost orbits are the most stable. electrons in all the orbits around the nucleus have the same amount of energy. electrons in the orbit closest to the nucleus have the least amount of energy. electrons absorb or release the same amount of energy independent of the energy levels.