It’s because new discoveries are made all the time sometimes what was considered right may be found out to be wrong
Answer:

Explanation:
Hello,
In this case, due to the volume displacement caused the by the object's submersion, it's volume is:

In such a way, considering the mathematical definition of density, it turns out:

Rounding to the nearest tenth we finally obtain:

Regards.
Answer:
a. BH₃
Explanation:
According to the octet rules, atoms reach stability when are surrounded by eight electrons in their valence shell when they combine to form a chemical compound.
From the options, the only compound in which the central atom does not meet the octet rules is BH₃. The central atom is boron (B), which has 3 electrons in its valence shell. When B is combined with hydrogen (H), 3 electrons from the 3 atoms of H are added. The total amount of electrons is 6, fewer than 8 electrons needed to meet the rule.
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