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GATE CSE 2025 Session 2 Q30: Match language classes to closure properties

Question

Consider the two lists List I and List II given below:

List IList II
(i) Context free languages(a) Closed under union
(ii) Recursive languages(b) Not closed under complementation
(iii) Regular languages(c) Closed under intersection

For matching of items in List I with those in List II, which of the following option(s) is/are CORRECT?

Try it: multiple select: one or more correct options

Select one or more options
Select all correct options. No negative marking, no partial marks.
Show answer and explanation

Answer: B, C (official GATE 2025 final answer key)

Concept used: An option is correct when every pair in it is a true statement; CFLs are closed under union but not complement, while recursive and regular languages are closed under all three operations.

First step: Mark each of the nine pairs true or false, then keep the options whose three pairs are all true.

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Source: official GATE 2025 Session 2 CS question paper and final answer key, organised by IIT Roorkee. Question paper · Answer key

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