At ground level, nitrous oxides are bad enough, but when up high

Question

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At ground level, nitrous oxides are bad enough,  but when up high, atmospherically they  bond with free ions to create dangerous smog particles.

A) but when up high, atmospherically they

B) however, it is in the upper atmosphere in which it may

C) but in the upper atmosphere, they

D) however, but once in the upper atmosphere it is known to

E) as in the upper atmosphere they

generis · Answer

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PyjamaScientist · Answer

The intended meaning in my opinion is-   Nitrous oxides are bad enough on the ground level. And in the upper atmosphere, they bond with free ions to create dangerous smog.

We can eliminate  (B) and (D)  for   S-V  disagreement . " It " is wrong here.

Only (A) (C) (E) remain.
Among these, (A) can be eliminated for using "atmospherically", it should be a noun depicting the place of bonding between NO and free ions. "Atmospherically" makes it an adverb modifying the action of bonding (how bonding was done). That's nonsensical.

Between (C) and (E) I am not sure either can be true. Grammatically, only option (C) stands but the meaning is not entirely clear. It would have been better if there weren't a " but ".  But   depicts a change of thoughts/reversal of flow. Here, both the actions are in the same direction. There's no change in direction of some story, so the usage of " but " since out of place.
Example. 
(1) I love my work,  but   it's becoming too demanding.
(2) There has been a rise in wages,  but   the inflation rate has risen exorbitantly simultaneously, killing off all the gains of raised wages.
As you can see from the above examples,  usage of " but " indicates  two contrasting ideas  or to  introduce an added statement, usually, something that is different from what you have said before  . So, (C) is fishy to me for that reason.

If you have to use "but" then it would have made much more sense if the meaning in the sentence was something like- 
 (a) Nitrous oxides are bad on ground level, but they are beneficial in the upper atmosphere for they reflect harmful UV rays.  
OR 
 (b) Nitrous oxides are bad enough on ground level, but they are even more dangerous in the upper atmosphere.

I think the author wants to imply the  second usage  here. But, the shift between the ideas is not clearly implied. There has to be a shift in ideas. You may say that both the ideas in example (b) are in the direction, and you are right, they are, but they are related events depicting a slight difference between the level of nitrous oxides impact. The way the statement is written, it shows Nitrous oxides' two impacts. And the correct flow in my opinion would be: Nitrous oxides are bad enough on the ground level, and they bond with free ions in the upper atmosphere to create dangerous smog.

Option (E) on the other hand, though it keeps the two ideas in the same direction, it is grammatically wrong. 
At ground level, nitrous oxides are bad enough,  as in the upper atmosphere they  bond with free ions to create dangerous smog particles.
It joins dependent clause WITH an Independent clause with just a comma.

Boho · Answer

At ground level, nitrous oxides are bad enough,  but when up high, atmospherically they  bond with free ions to create dangerous smog particles.

"At ground level " is a Prepositional phrase modifying clause "nitrous oxides are bad enough" =Independent clause

in the next portion of the sentence a contrast is introduced so let us review options

A) but when up high, atmospherically they

"when" is not appropriate to use in this context as we are not referring to time rather to positions also atmospherically is not idiomatic

B) however, it is in the upper atmosphere in which it may
"It" does not match in number

C) but in the upper atmosphere, they
Correct

D) however, but once in the upper atmosphere it is known to
Pronoun do not match in number

E) as in the upper atmosphere they
as is not the right connector to combine two independent clauses also contrast is missing

I mark (C) on the basis of my POE

PyjamaScientist · Answer

You sure the second part is an IC? An IC is a clause that can stand on its own.  as in the upper atmosphere they bond with free ions to create dangerous smog particles  this can not stand on its own. Hence, this is a dependent clause connected with the main Independent clause with just a comma, which is wrong. If it had  subordinating conjunction / relative pronouns , then it would be correct.
 Note: Dependent clauses begin with subordinating conjunctions: after, although, as, because, before, if, once, since, that, unless, until, when, why, etc. OR they begin with relative pronouns: that, which, whoever, whom, who, whose. 
 
Example: Tom was playing video game (IC),  while   Sarah and Jasmine were cooking (DC).

Boho · Answer

IMO: If you see second part "in the upper atmosphere, they bond with free ions to create dangerous smog particles" they unambiguously refers to subject of the previous clause i.e nitrous oxides and has it's own main verb i.e bond. so second part with a subject and main working verb is an IC IMO. "But" is connector that brings the contrast required to tie two ICs together. PyjamaScientist please feel free to highlight any miss in my analysis. Cheers

PyjamaScientist · Answer

What is the "contrast" here?
You said "but" is correct as it brings out the contrast between the two ICs. What is the contrast here?
I will give you some examples of contrasts.
A. She's a very hard-working person (IC), but she is not very imaginative (IC).
B. You can invite Keith to the party (IC) but do not invite his friend Mark (DC).

Boho · Answer

The original sentence intends to say that with no hesitation, we know nitrous oxides at ground levels are bad enough to cause some threats but in the upper atmosphere, they combine with free ions to create dangerous smog particles that may be fatal to life.

So contrast is Severity of the cause at ground level and higher altitude. Contrast, IMO, does not necessarily require two entities to be polar opposite. even differentials in the same polarity are considered contrasts.

I.e Driving can be risky, but driving at high speeds can be fatal.

Hope it helps

PyjamaScientist · Answer

1. I don't think the author wants to present any "contrast" here. The same meaning can be imparted by the usage of simple "and". Nitrous Oxides are bad enough on ground levels, and they bond with free ions in the upper atmosphere to create Y. It's just stating two facets of the same thing.
Eg. Boho is a good academician, and he is a brilliant singer. If I have to use "but" here, I should introduce  some   contrast like this-
Eg. Boho is a good singer, but he can only sing in Swahili.

2. I agree that contrast does not have to be the necessarily polar opposite, which is why if you look at my first post here, I have mentioned an example of milder contrast between the two related sentences. So, I agree with that.

And I also chose (C), but have reservations due to reasons stated above.

generis · Answer

Boho  and  PyjamaScientist  , now, this is the sort of discussion that I like to see. +1 to each of you.

Irrespective of answer, you are both engaged, and engaged in interesting critical thought at that. Well done.

Shikhar22 · Answer

I don’t think it’s the best sentence in general. But among the options available, C seems like the safest choice.

Posted from my mobile device

zhanbo · Answer

My answer is  (C) . It took me 01:07.

(A) After reading this version twice, I managed to get its meaning. The use and location of "atmospherically" is rather peculiar, but it might be allowed as a jargon in scientific discourse. Keep for now.

(B) Comma splice.

(C) A better version than (A). "in the upper atmosphere" is much more intelligible than "when up high, atmospherically". 
 Reject (A) and keep (C).

(D) "however" and "but" are redundant. more specifically, "however" should not be removed. (If "but" were removed instead, it would result in comma splice.)
Moreover, "it" cannot be used to refer to "nitrous oxides", an error also present in option (B).

(E) "as" is used to show similarity, not for contrast, as is the case here.

Crytiocanalyst · Answer

A) but when up high, atmospherically they
'when up high' isn't the best of the phrases , moreover upper atmospere has a better clarity in conveying the meaning therefore out

B) however, it is in the upper atmosphere in which it may
comma is unnecssary since these are dependent clause therefore out

C) but in the upper atmosphere, they
THe meaning along with the contrast is fine therefore let us hang on to it

D) however, but once in the upper atmosphere it is known to
'however' , 'but' , both addition in the sentence is unnecessary to showcase the contrast therefore out

E) as in the upper atmosphere they
as is best used in comparison which is not the case therefore out

Therefore IMO C

At ground level, nitrous oxides are bad enough, but when up high

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GMAT Sentence Correction (SC - EA only) Questions

At ground level, nitrous oxides are bad enough, but when up high

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