Guys I have encountered two such questions which pose the problem of using "which".
First, does someone properly know what "which" modifies when it has

1) a compound noun preceding it (Does it modifies one of them or both?)
2) a clause (separated by comma) with a noun just before the comma (Does it modifies the whole clause or just the noun?)
3) a clause which has a subject and a prepositional phrase (Does it modifies the whole clause or just the prepositional phrase?)

The two questions are as follow;

1) Executives and federal officials say that the use of crack and cocaine is growing rapidly among workers, significantly compounding the effects of drug and alcohol abuse, which already are a cost to business of more than $100 billion a year.

(A) significantly compounding the effects of drug and alcohol abuse, which already are a cost to business of
(B) significantly compounding the effects of drug and alcohol abuse, which already cost business
(C) significantly compounding the effects of drug and alcohol abuse, already with business costs of
(D) significant in compounding the effects of drug and alcohol abuse, and already costing business
(E) significant in compounding the effects of drug and alcohol abuse, and already costs business


2) Declining values for farm equipment and land, the collateral against which farmers borrow to get through the harvest season, is going to force many lenders to tighten or deny credit this spring.
(A) the collateral against which farmers borrow to get through the harvest season, is
(B) which farmers use as collateral to borrow against to get through the harvest season, is
(C) the collateral which is borrowed against by farmers to get through the harvest season, is
(D) which farmers use as collateral to borrow against to get through the harvest season, are
(E) the collateral against which farmers borrow to get through the harvest season, are


I know both of these questions have been discussed in detail but no consensus had been reached about the rules regarding "which".
Please help me.

CB

"Which" can be used in either cases and can replace "that" to introduce restrictive clauses.

Check this link for more explanation:

http://www.bartleby.com/64/pages/page39.html
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Trying hard to conquer Quant.

It gives wrong meaning to the sentence. What I interpreted is the drug and alcohol abuse business is costing $100billion. (It means the business is worth $100billion).
The intended meaning is the drug and alcohol abuseis costing the business $100billion (loss of $100billion).

B and E are correct..
For the second one D was also a concern.

"the collateral" is modifying "farm equipment and land ". It is an appositive.

I am still not sure what "which" is replacing ni that sentence.

alright i am retarded. figured it out.

Declining values for farm equipment and land, the collateral against which farmers borrow to get through the harvest season, are

Brajesh: for Q1

which should qualify the noun preceeding it correct?

then why isnt it effects and not abuse here ?

is it 'cos of of?

I know you asked experts to respond to these questions but I figured I think out loud and see if others agree with me or correct me otherwise!

In my experience ‘which’ more often than not represents the noun immediately before it and actually Manhattan SC makes such exclusive point. But in absence of such an option or other better options, we can use ‘which’ as ‘that’, meaning working in the context rather than the noun immediately before it.

In 1) I pick B because I do not have any other option which fits well, all other 4 choices seems to have grammatical errors. In ‘B’ ‘which’ is not referring to the noun(s) before it but I have no options other than B.

2) Here ‘D’ and ‘E’ are the two valid options (you can negate others because the use of ‘is’ since ‘values’ is a plural’). ‘which’ in D is referring to the effect of ‘declining values for farm equipment and lands’ not the nouns before it. This gives me enough reasons to negate it since I have better option available in E. But in absence of ‘E’ we might not have any choice but to pick D.

Well, "Drug and Alcohol abuse" is singular so we need singular verb "costs".

- Brajesh

i was talking about E.