What characteristics of water molecules make it unique?

Water molecules are polar, so they form hydrogen bonds. This gives water unique properties, such as a relatively high boiling point, high specific heat, cohesion, adhesion and density.

Because water seems so ubiquitous, many people are unaware of the unusual and unique properties of water, including:

Boiling Point and Freezing Point.

Surface Tension, Heat of Vaporization, and Vapor Pressure.

Viscosity and Cohesion.

Solid State.

Liquid State.

Gas State.

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.