What is the absolute refractory period? Choose the correct option. a. The period when the firing frequency is at about 1000 Hz b. The time period of about 1 msec after an action potential before another one can be initiated c. The time period of several milliseconds when it is difficult to initiate another action potential due to sodium channel inactivation d. The time period when the membrane potential stays hyperpolarized until the voltage-gated potassium channels close

 The time period of about 1 msec after an action potential before another one can be initiated b

Explanation:Absolute refractory period is the time after an action potential onset when no amount or how strong a stimulus is can cause  a second action potential. it is always the time period of 1 m sec between an initiated action potential and an impending  next initiated one with the the maximum firing frequency at about  1000 impulses per second.

The absolute refractory period is as a result  of molecular processes that triggers the action potential known as sodium channels(tiny pore nerves) . Now the sodium channels exist in three states which are open, close and inactivated states. At rest, the sodium channel is closed, but when a there is an electrical  stimulation, the sodium channel opens up to respond to that stimulus which after it passes to the inactivated state, in which the the spores are closed and  no matter how strong or the amount an impending next stimulus is, will not cause the pore to open until it has recovered and returned back to the closed state.

supongo que te refieres al paralaje estelar (observable).

si es así, entonces se puede inferir que la estrella está a más de 200 parsecs.

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.