Atoms, the smallest unit of matter, are made up of an equal number of

OFFICIAL EXPLANATION



Atoms, the smallest unit of matter, are made up of an equal number of protons and electrons, but if a single electron is lost or gained, it becomes an ion, a charged particle that can combine with other ions to form an electrovalent bond.


A) Atoms, the smallest unit of matter, are made up of an equal number of protons and electrons, but if a single electron is lost or gained,

B) An atom, the smallest unit of matter, is made up of an equal number of protons and electrons, but if the atom loses or gains a single electron,

C) Atoms, the smallest unit of matter, are made up of an equal number of protons and electrons, but if a single electron is lost or gained from them

D) The smallest unit of matter, atoms are made up of an equal number of protons and electrons, and when a single electron is lost or gained,

E) Made up of an equal number of protons and electrons, an atom, the smallest unit of matter, until a single electron is lost or gained,

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The sentence means that an atom
-- is the smallest unit of matter and
-- has an equal number of protons and electrons
BUT when the atom either loses or gains a single electron
-- the atom becomes an ion
The sentence ends with a dispensable appositive that describes an ion: a charged particle that can combine with other ions to form an electrovalent bond

***
• Split #1: Pronoun/antecedent agreement

It in the non-underlined portion lets us know that the subject is singular.
IT requires the singular ATOM as its antecedent.

I did not mark the plural verb ARE with red because are agrees with atoms and I did not want to suggest that atoms disagreed with are.

Options A, C, and D incorrectly use atoms, plural.

Eliminate A, C, and D

• Additional problems with A, C, and D

The electron does not become an ion. The atom becomes an ion.
Options A and D create a very subtle meaning issue because IT almost certainly refers to electron, in which case the electron becomes the ion.

Could "it" refer to "unit"? -- -- Maybe: Now we have pronoun ambiguity. Does "it" refer to electron or to unit?
-- Probably not: to be perfectly parallel, the appositive modifer unit of matter should say units of matter. I left this issue alone because the easiest way to eliminate A, C, and D is the disagreement between the non-underlined IT and plural atoms.

I would not use this issue as a first basis upon which to eliminate an answer in these choices that use plural "atoms."

Suppose, though, that option A were written this way:

An atom, the smallest unit of matter, is made up of an equal number of protons and electrons, but if a single electron is lost or gained, it becomes an ion, a charged particle that can combine with other ions to form an electrovalent bond.

Compare to option B.
No contest. B wins. In my hypothetical option A, it seems as though the electron becomes the ion. At the least, we do not know whether the thing that becomes an ion is the electron or the atom.
The electron does not become the ion. The atom becomes the ion.

Option C - from them
The phrase is awkward, but the phrase does intervene to head off the meaning problem I just discussed.
Even if the sentence were okay otherwise, B does a better job at letting us know which thing becomes an ion.

• Split #2: Clarity vs. The Missing Verb or Unnecessary Pronoun or Babble

We are down to options B and E.
Sometimes options are laughably bad, as is E in this question.

warrior1991 's comment about option E made me laugh: "This sounds creepy."
Believe me, you will find a sentence or two in which that thought ought to enter your mind.



I quote the entire comment because he's right: describing an error may not be easy, but we can both insert the option into the sentence and compare that construction to (B); even if we cannot quite say what is wrong with (E), we can say, "B is better and E is worse. Bye E. The end."

Option E contains one of these errors
1) if we say that the first part of the sentence ends with "gained," then atom lacks a verb.
2) we could also say that IT comes between the subject, atom, and the verb, becomes, in which case we have an unnecessary pronoun
3) the sentence structure in (E) is not nearly as clear as that in (B)

Answer B

COMMENTS

firas92 , you also made me laugh, grousing (or wondering) about what were indeed typos that I've corrected.

Although this question is unusually easy, every post contains some piece of advice or an approach or a comment that will apply to similar but harder questions.

These answers are very good to superb. Good work. Kudos to all.