The answer would be B. One region of the molecule has a small negative charge while another region has a small positive charge. However usually in polar bonds, charges or bond between the atoms are unequal (as opposed to having small equal charges).
Answer: Limitation: They may be more expensive and time consuming than lab experiments. Limitation: There is no control over extraneous variables that might bias the results. This makes it difficult for another researcher to replicate the study in exactly the same way.
Explanation:
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the answer is d. when more solute is added