Q3

[rfrahman]

3. What can be inferred about the lava that erupted in India?
a) No such comparison between the relative amount of carbon dioxide resulting from the meteorite and the volcano was ever made.
b) All we know is that the rock in the earth’s core is less dense, but we don’t know if it is denser than the rock above the earth’s core.
c) First off, it is the release of carbon dioxide that could have caused the climactic change, not the iridium hexafluoride. Secondly, this is too strong to say that iridium hexafluoride directly caused the climactic change.
d) Yes because the earth’s surface does not have much iridium but the sedimentary deposits from the eruption do. Line 35-38.
e) No comparison between the relative amount of iridium between meteorites and sedimentary deposits were made.

[yitsvi]

Hi, this is my first time posting, so please forgive me if I am not completely clear.

I selected choice C when I dissected this question as choice D seemed to contain a qualifier that was not mentioned in the passage. Nowhere does it say that the actual LAVA contained the iridium. It only states (in lines 43-45) that it would probably be emitted as iridium hexafluoride, a GAS! This implies that it was not actually contained in the lava which would make it classified as a liquid. LSAC seems to have selected a much broader definition of the word lava than I would be comfortable using. Choice D essentially refers to LAVA as a broader "volcanic discharge" that can include both.

I was ultimately more comfortable with choice C, despite the fact that the passage implied that iridium hexafluoride was only indirectly responsible for the change. My feelings for that were due to my belief that the word "Change" could be appropriately applied even when being used more indirectly.

Please reply if I have been comprehensible and if you can identify where I may have erred.

All the best!

[ohthatpatrick]

Yeah, I totally see your concern with (D).

This is probably a case where we have to go with the "more supportable" answer, even if we don't think it's adequately supported.

The idea with iridium never had ANYTHING to do with changing the climate (let alone changing it "dramatically", as (C) says).

Iridium is only discussed because it corroborated the idea of a possible meteorite impact having killed the dinosaurs. Scientists were like, "It IS weird that there was a bunch of iridium on the earth right when the dinosaurs died."

But iridium was never thought to impact the climate directly (or indirectly).

You can probably make peace with the whole "lava = gas+fluid" in the sense that diapirs are identified as blobs of molten rock (molten rock = lava).

Diapirs are blobs of lava, and a "diapir eruption would disperse iridium hexafluoride".