Atoms may have different numbers of neutrons. Atoms are the smallest fraction of an element that can exist, and still show the properties of the element. They consists of electrons (negatively charged), protons (positively charged), and neutrons (no charge). The number of electrons is equivalent to the number of protons normally however an atom may loose or pick up electrons and have a positive charge or negative charge. The number of neutrons in the nucleus may vary within a given element to give varieties of atoms we call isotopes.
A nebula is an interstellar cloud of "Dust and Gas"
A body of underground water, usually comprised of water saturated regolith, is permeable, and replenishes lakes and streams, is known as a aquifer.
Groundwater to be able to get into a rock with good porosity it must also have good permeability. For a rock to be permeable and for water to move through it, the pore spaces between the grains in the rock must be connected. Permeability is therefore a measure of the ability of water to move through a rock.
An aquifer is a body of rock and/or sediment that holds groundwater. Groundwater is the word used to describe precipitation that has infiltrated the soil beyond the surface and collected in empty spaces underground. There are two general types of aquifers confined and unconfined.
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B because it is a child of 2-5 years