CAT Prep: That vs. Which

“That” and “which” are two very tricky words in CAT Verbal. In some case these words are almost the same in use. Other times, they can be quite different.

“That” and “Which” as Relativizers and Demonstratives

Both “that” and “which” can serve as two different parts of speech. Each word can be either a relativizer or a demonstrative. A relativizer is a word that helps to add new information to a noun, or limits a noun to a specific category. A demonstrative is a word that points out the existence or location of a noun, or points out the existence of a fact/statement/idea.

“That” as a Relativizer

As a relativizer, “that” can ONLY limit a noun to a specific category. Relative phrases with “that” include phrases such as “the cat that has the stripes,” “the house that the president lives in,” “the man that I love,” and so on.

cat prep that which

“Which” as a Relativizer

“Which” can fulfill both of the possible functions of a relativizer: it can add information to a noun, or it can limit the noun to a specific category.

When “which” adds information to a noun, the phrase that starts with “which” is separated from the rest of the sentence by commas. Think of this kind of “which” relative phrase as an “extra” phrase. The sentence would be meaningful even if you removed the phrase. But the sentence has more information with the extra phrase that’s been added between the commas.

  • Example: India, which has the CAT exam, is home to the world’s most competitive business schools.

Above, you could also say “India is home to the world’s most competitive business schools.” The sentence is still perfectly meaningful with the relative phrase removed. It just contains less information.

“Which” can also be used to restrict a noun to just one category. In that case, the “which” phrase will not be separate from the rest of the sentence by commas, because it’s essential to the sentence’s meaning.

  • Example: The IIM is the group of business schools which designs the CAT.

Here, you can’t remove the “which” phrase and still have a complete thought. If you say “The IIM is the group of business schools,” it begs the question: what group of business schools? “The” marks the IIM as special, but why is it special? Without the “which” relative clause that limits the IIM to a special category, the sentence is less meaningful, and doesn’t communicate all of its important ideas. (Note that in this use, “which” is interchangeable with “that.” The business school which designs the CAT is the same thing as the business school that designs the CAT.)

“That” as a Demonstrative

As a demonstrative, “that” can do two things: it can indicate that a noun is distant, or it can point out an idea or thought.

“That” and distance


“That” is used to show that a noun is relatively far away. The distance can be physical distance (“that tree across the street”) or emotional distance (“that child is not my child). In contrast, closeness would be indicated by “this” (“this tree right next to me,” or “this is my child”).

“That” as a way to point out ideas

As a demonstrative, “that” can also point to the existence of an idea. “That” can demonstrate that someone has thought or expressed an idea, as in “She feels that it is not yet time to have a meeting.” “That” can also reference an thought or idea that has already been expressed, as is “She doesn’t want to have a meeting. That is odd, because she usually likes to have meetings.”

“Which” as a Demonstrative

When it’s used as a demonstrative, the word “which” is much more limited than “that.” Demonstrative “which” can only be used to to reference a thought or idea that’s already been expressed. For instance, you could say “She doesn’t want to have a meeting, which is odd, because she usually likes to have meetings.”

Notice that when “which” is used to reference a previously expressed idea, it behaves a lot like “that.” But it’s not exactly the same. Can you see the difference? As a demonstrative of ideas, “which” appears in the middle of the sentence and introduces a dependent clause (“…which is odd, because…”). In contrast, when “that’ serves the same grammatical purpose, it’s the start of a new sentence that references an idea in the previous sentence (“That is odd, because…”).

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