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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Answer:
nonpolar covalent bond: A covalent bond in which the bonding electrons are shared equally between the two atoms. polar covalent bond: A covalent bond in which the atoms have an unequal attraction for electrons and so the sharing is unequal.
Answer:

Explanation:
The given reactions are:
PbCl2(aq)⇌Pb2+(aq)+2Cl−(aq) 
AgCl(aq)⇌Ag+(aq)+Cl−(aq) 
Required reaction is:
PbCl2(aq)+2Ag+(aq)⇌2AgCl(aq)+Pb2+(aq)

Answer: Heterogenous mixtures are the ones in which we can see the different components clearly. Air is considered to be homogenous, because we don't see the different noble gases' particles floating around. Salt water is also homogenous, because salt dissolves almost completely into water, becoming hard to see without the proper equipment salt particles in it. Steel is also homogenous, since the metals that compose it are mixed during the heating. The only heterogenous would be soil, because we can see different particles in it, with different sizes, shapes, colors, etc without having to use special equipment.
Answer: B. it will scatter a beam of light
Explanation: hope it is helpful........