• Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep
  • e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer
  • Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors
  • Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • The Princeton Review
    FREE GMAT Exam
    Know how you'd score today for $0

    Available with Beat the GMAT members only code

    MORE DETAILS
    The Princeton Review

IR + CR: rock varnish, iron, manganese, bacteria, limonite

This topic has 2 member replies
nicktim Junior | Next Rank: 30 Posts Default Avatar
Joined
04 Jan 2013
Posted:
20 messages

IR + CR: rock varnish, iron, manganese, bacteria, limonite

Post Mon Jun 24, 2013 11:32 pm
I am very confused with this CR/inference-embedded IR question. I found the passage confusing and I could not understand the meaning of the passage after reading it a couple of times. Can an expert please help a fella out? Smile

When tackling a "two-part analysis" type of question, should we try to come up with both solutions simultaneously, or should we tackle each question?

-----

Rock varnish is typically rich in iron and manganese, with the presence of manganese due to bacteria on the surface of the rock. Because the bacteria would not survive on the surface of rocks in the colder, continuously frozen, reaches of Antarctica, scientists were not surprised to discover that rock varnish in the Thiel Mountains area of Antarctica consists only of limonite, a form of oxidized iron. This had penetrated from the surfaces of the rocks into the cracks. However, although moisture is essential to the movement of limonite, snow has not melted in the Thiel Mountains in recent times.

Indicate which statement in the table the given information most strongly suggests is true, and the statement that the given information most strongly suggests is false. Make only two selections, one in each column.

A. Moisture is required for the presence of significant amounts of manganese in the environment.
B. Moisture is not required for the presence of significant amounts of manganese in the environment.
C. When temperatures in a continuously frozen location increase to above freezing, cracks in rocks there begin to take in rock varnish containing significant amounts of manganese.
D. Rock varnish that is especially rich in iron is mostly found in extreme cold.
E. Manganese is unable to penetrate into cracks in significant amounts.
F. Temperatures on rocks in the Thiel Mountains were above freezing at some point in the past.

-----

Answers:
What must be true? F
What must be false? C

  • +1 Upvote Post
  • Quote
  • Flag
srcc25anu Master | Next Rank: 500 Posts Default Avatar
Joined
11 Jun 2010
Posted:
423 messages
Followed by:
2 members
Upvotes:
86
Target GMAT Score:
720+
Post Wed Jun 26, 2013 11:44 am
F is true. Since rock varnish in Theil area consists of limonite, it must have penetrated down at some point in the past. Although, the snow did not melt in recent times, this does not exclude the possibility that it never melted. In fact, it must have melted sometime ago (in past) since it did not melt in recent past.

C is False. When temperatures in a continuously frozen location increases to above freezing, cracks in rock begin to take in rock varnish BUT such rock varnish would be rich in iron and not manganese as presence of manganese is due to bacteria on rock surface and bacteria cannot survive on rock surface in such frozen locations. So it is unlikely to discover manganese in rock cracks in Antartica.

  • +1 Upvote Post
  • Quote
  • Flag
kutlee Senior | Next Rank: 100 Posts
Joined
14 Aug 2007
Posted:
90 messages
Upvotes:
2
Post Tue Apr 07, 2015 8:18 pm
Good question.
F should be true because moisture or water is essential to carry limonite into the cracks - So F should be true.
For statement that is not true, i went by elimination

A. Moisture is required for the presence of significant amounts of manganese in the environment.
B. Moisture is not required for the presence of significant amounts of manganese in the environment.
A and B talks about environment. Here we know only about rocks. So we don't know the validity of these statements. So ignore.

C. When temperatures in a continuously frozen location increase to above freezing, cracks in rocks there begin to take in rock varnish containing significant amounts of manganese.
Hold on to C. Cracks are filled with limonite. Not Manganese. This could be the answer

D. Rock varnish that is especially rich in iron is mostly found in extreme cold.
D states something about iron. We have data about iron oxide. Both are chemically different. Confusing. Still better answer is C

E. Manganese is unable to penetrate into cracks in significant amounts.
We don't have data about ability of manganese to penetrate into rocks. So ignore.
F. Temperatures on rocks in the Thiel Mountains were above freezing at some point in the past.

  • +1 Upvote Post
  • Quote
  • Flag

Top First Responders*

1 GMATGuruNY 69 first replies
2 Rich.C@EMPOWERgma... 41 first replies
3 Brent@GMATPrepNow 40 first replies
4 Jay@ManhattanReview 24 first replies
5 Terry@ThePrinceto... 10 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

Most Active Experts

1 image description GMATGuruNY

The Princeton Review Teacher

134 posts
2 image description Jeff@TargetTestPrep

Target Test Prep

111 posts
3 image description Rich.C@EMPOWERgma...

EMPOWERgmat

111 posts
4 image description Scott@TargetTestPrep

Target Test Prep

103 posts
5 image description Max@Math Revolution

Math Revolution

92 posts
See More Top Beat The GMAT Experts