<span>C. polar bonds and asymmetrical structure
If the molecule contains polar bonds but it has a symmetrical structure, the polar bonds will cancel each other out so the overall molecule will be non-polar.
On the other hand, if the molecule contains polar bonds but has an asymmetrical structure, then the polar bonds won't cancel each other out, so the overall molecule ends up being polar.
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No one can do that by him or her self
A large atom means that the radius would be large, meaning that the effective nuclear charge is low, therefore a lower electronegativity based on the periodic table. A smaller atom would mean the opposite, therefore a higher electronegativity. This combination would mean that the new molecule is polar.
Also, to answer your question, it would be most likely different from both atoms, as size doesn't really matter in a compound's properties.