What is unequal sharing of electrons

Covalent bond between two atoms with unequal electronegativities results in unequal sharing of electrons. These types of covalent bonds are called polar bonds because the electron distribution or charge is unevenly distributed or polarized. .

Explanation:

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

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the darker peppered moth species were favored due to the fact that the industrial revolution had made all the nearby trees a darker color instead of white.