Spectroscopic analysis has revealed the existence of frozen nitrogen

(A) There is no more frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane.
- Out. Does not tells us there is more frozen nitrogen than frozen carbon monoxide/methane


(B) Until space probes reach Pluto, direct analysis of the atmosphere is impossible.
- Out of scope

(C) There is no frozen substance on the surface of Pluto that vaporizes more readily than methane but less readily than carbon monoxide.
- This one explains why there is a decreasing abundance from nitrogen to carbon monxide to methane.

(D) Nitrogen is found in the atmosphere of a planet only if nitrogen ice is found on the surface of that planet.
- Does not explain the abundance. We're already told the ice vaporize to produce an atmosphere, so this choice does nothign more than to give a redundant premise

(E) A mixture of nitrogen, carbon monoxide, and methane is characteristic of the substances from which the Solar System formed.
- out of scope

I'll go with C

Hello, look at red part.
nitrogen vaporizes the fastest, followed by carbon monoxide, and methane

There is no frozen substance on the surface of Pluto that vaporizes more readily than methane Is it not carbon monoxide and nitrogen?

...but less readily than carbon monoxide
Is it not methane ?

Thanks

This question puzzles me too. The question stem could lead to many good choices but the choices given are not exactly what you'd expect. Anyways here's what I think.

Fact: There are frozen N2, Methane, and CO on the surface of Pluto.
Fact: Such ice tend to vaporize and produce an atmosphere.
Fact: The proportion of any gas depends on how readily the corresponding ice vaporizes.
Conclusion: The components of Pluto's atmosphere are N2, CO, and methane, with N2>CO>Methane.

Ask for assumptions.

The obviouse assumption I can see from the passage is that N2 is more readily vaporized CO follows, and Methane is least readily vaporized.

(A) There is no more frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane.
This almost feels like the only possible correct answer that they want to test you. However it should have been "there is no less frozen nitrogen than carbon monoxide or methane", instead of "no more... than". The way it is formulated now, it doesn't seem to be an assumption that the scientists need to make. Even if there is more frozen N2 than the others, this would make the N2 gas more abundant than the others, and will not overthrow the conclusion.

(B) Until space probes reach Pluto, direct analysis of the atmosphere is impossible.
This is a bit out of scope I think.

(C) There is no frozen substance on the surface of Pluto that vaporizes more readily than methane but less readily than carbon monoxide.
This looks like a trap. What one is supposed to think is that "well what if there's some other frozen gas that is not discovered whose readiness to vaporize is between Methane and CO?" However, I think the way the conclusion is spelled out has ruled out this possibility. The conclusion says "The components of Pluto's atmosphere are" this this and that. In other words, it didn't say these three are in the atmosphere. The subtle difference to me is that the second way you can say other things may also be in the atmosphere, but the first way you are sure the only components are these three.

(D) Nitrogen is found in the atmosphere of a planet only if nitrogen ice is found on the surface of that planet.
As I said before, the problem with this is "only if".

(E) A mixture of nitrogen, carbon monoxide, and methane is characteristic of the substances from which the Solar System formed.
I tried to see if there's something here. But it looked out of scope to me.

Therefore among the five choices C looks like the closest to me.

Spectroscopic analysis has revealed the existence of frozen nitrogen, methane, and carbon monoxide on the surface of Pluto. Such ices have a tendency to vaporize, producing an atmosphere. Since the proportion of any gas in such an atmosphere depends directly on how readily the corresponding ice vaporizes, astronomers have concluded that the components of Pluto’s atmosphere are nitrogen, carbon monoxide, and methane, in order of decreasing abundance.

The astronomers’ argument relies on which one of the following assumptions?

(A) There is no more frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane.
(B) Until space probes reach Pluto, direct analysis of the atmosphere is impossible.
(C) There is no frozen substance on the surface of Pluto that vaporizes more readily than methane but less readily than carbon monoxide.
(D) Nitrogen is found in the atmosphere of a planet only if nitrogen ice is found on the surface of that planet.
(E) A mixture of nitrogen, carbon monoxide, and methane is characteristic of the substances from which the Solar System formed

Source : LSAT PrepTest 21

OA is C
I agree with the OA. However, I have a doubt with choice A. If we use the negation technique, and we assume that "there is MORE frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane". The conclusion could be weakened. Let me explain:

The argument says that the the RATE OF EVAPORIZATION of each ice (readiness) determines the proportion of each gas in the atmosphere. However, let's suppose that Nitrongen (the most abundant in atmosphere) has the lowest rate of evaporation but it is the most abundant as ice on the surface ( my negation technique). Nitrogen would be the most abundant in atmosphere not by the rate of evaporization, but by the amount of nitrogen on the surphace. The reasoning of the author would be weakened
Thanks!

Hi Metallicafan,

It seems as though you are making your own assumption when you defend (A). That for there to be more nitrogen in the atmosphere, there need only be more frozen nitrogen. If that were the case, then the answer could be (A).

Also, I think that when the argument says, "Since the proportion of any gas..." that is a premise upon which the conclusion (the distribution of methane, etc.) is based. When looking for an assumption, we want to find that gap between the premise and the conclusion.

Let me know if that makes sense

The conclusion states that, in decreasing abundance, the elements on Pluto are nitrogen, carbon monoxide, and methane. This conclusion assumes that there are no other elements that would disrupt this ranking. Namely, an element that would vaporize less readily than carbon monoxide or more readily than methane.

Hope that helps!

[quote="chunjuwu"]Spectroscopic analysis has revealed the existence of frozen nitrogen, methane, and carbon monoxide on the surface of Pluto. Such ices have a tendency to vaporize, producing an atmosphere. Since the proportion of any gas in such an atmosphere depends directly on how readily the corresponding ice vaporizes, astronomers have concluded that the components of Pluto’s atmosphere are nitrogen, carbon monoxide, and methane, in order of decreasing abundance.

The astronomers’ argument relies on which one of the following assumptions?

(A) There is no more frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane.

(B) Until space probes reach Pluto, direct analysis of the atmosphere is impossible.

(C) There is no frozen substance on the surface of Pluto that vaporizes more readily than methane but less readily than carbon monoxide.

(D) Nitrogen is found in the atmosphere of a planet only if nitrogen ice is found on the surface of that planet.

(E) A mixture of nitrogen, carbon monoxide, and methane is characteristic of the substances from which the Solar System formed.


Let's break down into premises and conclusion

Premsie 1:Spectroscopic analysis has revealed the existence of frozen nitrogen, methane, and carbon monoxide on the surface of Pluto.
Premise 2:Such ices have a tendency to vaporize, producing an atmosphere.
Premise 3: The proportion of any gas in such an atmosphere depends directly on how readily the corresponding ice vaporizes.

Conclusion: astronomers have concluded that the components of Pluto’s atmosphere are nitrogen, carbon monoxide, and methane, in order of decreasing abundance.
As per the conclusion N2> CO> CH4

Think for a moment how astronmers conclude "N2> CO> CH4" based on the above primises
Possible assumption: rate of evaporation of N2 is greater than CO and rate of evoparation of CO is greater than CH4.
In one premise it was wtitten any (hilighted in red).
on the basis of this
No gas comes in between N2 and CO and in between CO and CH4.

Let's POE

(A) IncorrectThere is no more frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane. we cannot assume this because nothing related to this is indicated in the passage. So, A is Irrrevelant.

(B) IncorrectUntil space probes reach Pluto, direct analysis of the atmosphere is impossible. Out of scope. No way this helps us to achieve the conclusion

(C) CorrectThere is no frozen substance on the surface of Pluto that vaporizes more readily than methane but less readily than carbon monoxide. This mathches with our prethinking.
Don't forget to negate the correct option to checkoption's validity. If negated option invalidate the conclusion the that assumption is valid assumption.
Let's negate
There is no frozen substance on the surface of Pluto that vaporizes more readily than methane but less readily than carbon monoxide. The negated version says there is some frozen substance in between then. Hence shatters our conclusion.

(D) IncorrectNitrogen is found in the atmosphere of a planet only if nitrogen ice is found on the surface of that planet. Nothing such can be assumend.

(E) IncorrectA mixture of nitrogen, carbon monoxide, and methane is characteristic of the substances from which the Solar System formed. This option is of no help

Hence C

Here is my analysis

Argument structure
Conc: Astronomers have concluded that the components of Pluto's atmosphere are nitrogen, carbon monoxide, and methane, in order of decreasing abundance.
Basis of concusion (P): Since the proportion of any gas in such an atmosphere depends directly on how readily the corresponding ice vaporizes,
P1: Spectroscopic analysis has revealed the existence of frozen nitrogen, methane, and carbon monoxide on the surface of Pluto.
P2: Such ices have a tendency to vaporize, producing an atmosphere.

Pre-thinking
First thing to notice when you start reading the argument is that S analysis revealed the existence of 3 elements in Pluto (so you assume that could be more elements). But when you reach the conclusion, the author says that Astronomers have concluded that the components of Pluto's atmosphere are the same 3 elements (so no more element in Pluto's atmosphere). Now, the basis of the conclusion says that the abundance of each element in the atmosphere depends on how easily the frozen elements evaporate. Because the conclusion establishes an order of the abundance of each gas in Pluto's atmosphere, one can assume that there are only 3 element, that Nitrogen is the most abundant, and that CO is the least abundant.

Answer choice analysis
(A) There is no more frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane. Incorrect
No clue about the abundance of frozen gases in Pluto's surface.

(B) Until space probes reach Pluto, direct analysis of the atmosphere is impossible. OFS.

(C) There is no frozen substance on the surface of Pluto that vaporizes more readily than methane but less readily than carbon monoxide. Correct!
Aligned with pre-thinking. If negated, the conclusion of scientists is shattered.

(D) Nitrogen is found in the atmosphere of a planet only if nitrogen ice is found on the surface of that planet. OFS
Too broad in scope.. we are talking about Pluto in the argument. We can not make that generalization.

(E) A mixture of nitrogen, carbon monoxide, and methane is characteristic of the substances from which the Solar System formed. OFS
Too broad in scope.. we are talking about Pluto in the argument. Nothing is mention about Solar System

Spectroscopic analysis has revealed the existence of frozen nitrogen, methane, and carbon monoxide on the surface of Pluto. Such ices have a tendency to vaporize, producing an atmosphere. Since the proportion of any gas in such an atmosphere depends directly on how readily the corresponding ice vaporizes, astronomers have concluded that the components of Pluto’s atmosphere are nitrogen, carbon monoxide, and methane, in order of decreasing abundance.

The astronomers' argument relies on which one of the following assumptions?

(A) There is no more frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane.
This is part of conclusion which can be inferred, not an assumption to reach the conclusion.

(B) Until space probes reach Pluto, direct analysis of the atmosphere is impossible.
Irrelevant.

(C) There is no frozen substance on the surface of Pluto that vaporizes more readily than methane but less readily than carbon monoxide.
The abundance sequence: N2 > CO > CH4
The vaporization seq : N2 > CO > CH4

There is no 'x' such that N2 > CO > x > CH4

If there is any 'x' which satisfies the above condition, then conclusion that N2 > CO > CH4 will be wrong.

So, author has assumed it.

Correct.



(D) Nitrogen is found in the atmosphere of a planet only if nitrogen ice is found on the surface of that planet.

It is not only true about N2, but also for all of the gases.

(E) A mixture of nitrogen, carbon monoxide, and methane is characteristic of the substances from which the Solar System formed.
Irrelevant.

I agree completely with the way you analyze the structure of the argument. However, I disagree with the conclusion that C is the correct answer.

C is asserting something that is false according to the passage. From the given composition of the gases in the atmosphere, Nitrogen has to vaporize more readily than Carbon Monoxide. So the passage does assert that there is indeed a frozen substance that vaporizes more readily than Carbon Monoxide.

So my choice from what's given will be D but still, that too has problems of its own. If it is possible to have other sources for Nitrogen, then the vaporization phenomena no longer fully explain the composition of the atmosphere. However, since Nitrogen is the most abundant, the given ordering of the proportions will still hold.

Is my understanding correct? If so, is this a good question at all?

Spectroscopic analysis has revealed the existence of frozen nitrogen, methane, and carbon monoxide on the surface of Pluto. Such ices have a tendency to vaporize, producing an atmosphere. Since the proportion of any gas in such an atmosphere depends directly on how readily the corresponding ice vaporizes, astronomers have concluded that the components of Pluto's atmosphere are nitrogen, carbon monoxide, and methane, in order of decreasing abundance.

The astronomers' argument relies on which one of the following assumptions?

Spectroscopic analysis has revealed the existence of frozen nitrogen, methane, and carbon monoxide on the surface of Pluto. Such ices have a tendency to vaporize, producing an atmosphere. Since the proportion of any gas in such an atmosphere depends directly on how readily the corresponding ice vaporizes, astronomers have concluded that the components of Pluto's atmosphere are nitrogen, carbon monoxide, and methane, in order of decreasing abundance.

The astronomers' argument relies on which one of the following assumptions?

(A) There is no more frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane. - WRONG. It's about vaporization of the frozen components and not about amount that exists on surface.

(B) Until space probes reach Pluto, direct analysis of the atmosphere is impossible. - WRONG. Nothing sort of discussed or suggested.

(C) There is no frozen substance on the surface of Pluto that vaporizes more readily than methane but less readily than carbon monoxide. - CORRECT. This is confusing at first since only three components are there in the passage and the conclusion is about these components only. So anything other than these, if present in the atmosphere would nullify the conclusion. This option exactly nullifies that possibility so that conclusion remains intact.

(D) Nitrogen is found in the atmosphere of a planet only if nitrogen ice is found on the surface of that planet. - WRONG. Not necessarily true. This is a trap not because of what it says but how C is formulated.

(E) A mixture of nitrogen, carbon monoxide, and methane is characteristic of the substances from which the Solar System formed. - WRONG. Irrelevant.

Answer C.

Understanding the argument -
Spectroscopic analysis has revealed the existence of frozen nitrogen, methane, and carbon monoxide on the surface of Pluto. - Fact
Such ices have a tendency to vaporize, producing an atmosphere. - Fact
Since the proportion of any gas in such an atmosphere depends directly on how readily the corresponding ice vaporizes, astronomers have concluded that the components of Pluto's atmosphere are nitrogen, carbon monoxide, and methane, in order of decreasing abundance. - Supporting premise + Conclusion.
The supporting premise talks about "any gas," and the conclusion talks about three gases: "nitrogen, carbon monoxide, and methane, in order of decreasing abundance."

The minimum condition, missing premise, or the assumption is that there is no other material or gas. If there is any other material or gas, then the conclusion "the components of Pluto's atmosphere are nitrogen, carbon monoxide, and methane, in order of decreasing abundance" falls flat, as it can't be just these 3.

Option Elimination -

(A) There is no more frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane. - This option is a deception. This provides a comparison of abundance amongst "nitrogen," "carbon monoxide," and "methane." But that is immaterial, as the abundance or shortage in the atmosphere depends on the tendency to vaporize and not on the actual abundance. Another deception here is that it talks about all three gases; option C talks about two gases and doesn't even talk about Nitrogen. But if we understand the argument property, then we don't even need all, or not mentioning nitrogen is not an issue. Because the conclusion intends to say that only these three are in the atmosphere. So, we need to assume that there is no other substance or gas X in the atmosphere.

Say we negate this option: "There is more frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane." Then what? It can still be more on the surface and more in the atmosphere because it tends to vaporize. Even if it's less on the surface, it could still be more in the atmosphere. This is a classic distortion and the most popular wrong answer.

(B) Until space probes reach Pluto, direct analysis of the atmosphere is impossible. - Out of scope.

(C) There is no frozen substance on the surface of Pluto that vaporizes more readily than methane but less readily than carbon monoxide. - Negate this. Say there is. Then we can't say that these 3 make the Pluto atmosphere in decreasing abundance. Ok. The Deception here is that it doesn't even talk about "Nitrogen." But this assumption is so basic that it's easy to miss.

(D) Nitrogen is found in the atmosphere of a planet only if nitrogen ice is found on the surface of that planet. - It is found. Out of scope.

(E) A mixture of nitrogen, carbon monoxide, and methane is characteristic of the substances from which the Solar System formed. - "Solar System" is out of scope.

Well D. I think it is equivalent to saying that the only source of nitrogen is the ice. No nitrogen ice -> then no nitrogen.

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Well for C, what if there’s some other type of gas that doesn’t come from the evaporation of the ice?

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