Why does table salt (nacl) dissolve readily in water?
it is a hydrophobic substance.
it is a polar molecule.
it is an ionic compound.
it is a binary compound.

The correct answer is It is an ionic compound.

NaCl ( table salt) is an ionic compound as it is made up of positively charged sodium ion, which is bonded to the negatively charged chloride ion.

The negative part of NaCl is attracted by the positive part of the water molecule. Similarly, the positive part of NaCl is attracted by the negative part of the water molecule. Due to this, the table salt gets readily dissolved in water.

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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when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.