Jenny has a mixture of sand, sugar, common salt, and milk powder. she adds some water to the mixture. which of these can be separated easily from the mixture after adding water?

Sand

Sand can be separated easily from the mixture after adding water. Sand does not mix with water unlike sugar, common salt, and milk powder. Sand settles down like precipitates because it cannot float or dissolve like the others. Decantation technique can be used to separate sand from the mixture.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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i believe the answer is a or 1