Answer:
is a well-sustantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment.such fact- supported theories are not "guesses" but reliable accounts of the real worlds.
Resources that come from nature, some examples include: Water, Gold, Oil, Coal, Apples, Oranges, etc.
Answer:
A3+ and B-
Explanation:
Elements in group 13 have outermost electron configuration, ns2np1 hence they form trivalent positive ions.
Elements in group 17 have outermost electron configuration ns2np5 hence they form univalent negative ions.
This implies that, if element A is in Group 13 and element B is in Group 17, the ions formed are A3+ and B-.
Answer:

Explanation:
Hello.
In this case, given the formula:

Whereas E is the energy, h the Planck's constant and u the frequency of the photon. Thus, solving for it, we obtain:

Or also:

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