Jane had leukemia as a child and had to undergo numerous bouts of chemotherapy. she had associated the waiting room with nausea. now 35 years old, she had to take her mother to the same hospital for breast cancer treatment. she became nauseous while in the waiting room with her mother. her nausea best illustrates:

The nausea is considered to be an unconditioned response. An unconditioned response occurs when it is associated with an unconditioned stimulus causing a response to naturally occur in which would be classified as an unconditioned response after it has been previously associated with the unconditioned stimulus.

igneous rocks are formed by solidification of cooled magma (molten rock), with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.  

the composition depends on the source magma. there are almost a thousand types of composition found till now.  

hope this

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.