Ionized oxygen is known to contain large numbers of particles X and Y.

Question

Ionized oxygen is known to contain large numbers of particles X and Y. Repeated lab tests have shown that whenever particles X and Y collide, they produce particle Z. Since the air supply in the offices of the electrical power plant has been shown not to contain any Z at all, it is safe to conclude that that the oxygen in the offices' air supply has not become ionized.

The reasoning above is flawed because the author

A. confuses necessity and sufficiency
B. does not take into account the possibility of improper test conditions
C. relies on the assumption that if a phenomenon can take place, it is bound to take place
D. draws a conclusion despite evidence that is self-contradictory.
E. fails to take into account that other particles can be formed when particles X and Y collide

GMATking94 · Answer

The Q says that ionized Oxygen contains particles X & Y and they upon collision produce Z. Now since there is no Z present in office air, the argument concludes that the oxygen in office air is not ionized. One flaw which can be directly drawn from this is "What if there is no collision between the particles yet...which may be due to some reasons. Maybe lower density...blah..blah... so it is clearly a flaw.

Option (C) correctly depicts this flaw and is the right answer.

GogulaKrishnan · Answer

Any one please explain why A is wrong?

GogulaKrishnan · Answer

Any one please explain why A is wrong?

egmat · Answer

Hi GogulaKrishnan,

Good question. You're right that the argument has a conditional feel to it ("no Z,  therefore  no ionization"), and that's exactly what makes A look tempting. But let's see what A would actually require.

What "confuses necessity and sufficiency" means:  the author would have to take a condition that is only  sufficient  and treat it as  necessary , or vice versa - basically swap the roles in a stated rule. Classic example: "Studying hard is enough to pass" -> "so if you didn't study hard, you can't pass."

Why that's not what happens here.  Look at the chain the author actually builds:

- Ionized oxygen -> contains X and Y.
-  Whenever  X and Y  collide  -> they produce Z.
- No Z found -> so no ionization.

Every conditional in that chain is used in the correct direction. The author never flips a  sufficient  condition into a  necessary  one. So nothing is being "confused" between necessity and sufficiency.

Where the argument really breaks  is the hidden jump between "contains X and Y" and "X and Y collide." Ionization only guarantees that X and Y are  present  - it does  not  guarantee they actually collide. Z appears only  when  they collide, which is  possible but not certain . The author treats that possible collision as if it were bound to happen, so the absence of Z gets read as absence of ionization.

That "it can happen, so it must have happened" leap is precisely what  C  names - and it's a different error than the role-swap that A describes.

Quick way to feel the gap: "A spark  can  start a fire. No fire here - so there was no spark." The flaw isn't mixing up necessary vs.  sufficient ; it's assuming the spark was  bound  to catch. That's C, not A.

Answer: C

Ionized oxygen is known to contain large numbers of particles X and Y.

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GMAT Critical Reasoning (CR) Questions

Ionized oxygen is known to contain large numbers of particles X and Y.

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