A decline in sensory responsiveness that occurs when a stimulus is unchanging or repetitive is called .

Sensory Adaption

Explanation:

Stimuli, both external and internal, are sensed with the help of sensory receptors. These sensory receptors sense the change in internal or external conditions called stimuli and send the information to the central nervous system. The sensory information is processed and interpreted in the central nervous system which in turn makes a person aware of the sensed stimuli.

However, the constant presence of the same stimulus does not trigger the firing of the action potential as it occurred during the first few encounters. This is called sensory adaption. For example, chirping of birds is apparent when a person enters the countryside but becomes less apparent after a few days due to sensory adaption of ears.

when a reversible reaction is occurring in both directions at the same rate; the products and reactants do not change in concentration. a chemical reaction where the compound is broken into its constituent parts.