# CBSE UGC NET Computer Science Paper III Solved November 2017 - Part 3

21.       Pumping lemma for regular language is generally used for proving:
(1) whether two given regular expressions are equivalent
(2) a given grammar is ambiguous
(3) a given grammar is regular
(4) a given grammar is not regular
Answer: 4
22.       Which of the following problems is undecidable?
(1) To determine if two finite automata are equivalent
(2) Membership problem for context free grammar
(3) Finiteness problem for finite automata
(4) Ambiguity problem for context free grammar
Answer: 4
23.       Finite state machine can recognize language generated by ....................
(1) Only context free grammar
(2) Only context sensitive grammar
(3) Only regular grammar
(4) any unambiguous grammar
Answer: 3
24.       The language L = {ai b ci | i ≥ 0} over the alphabet {a, b, c} is:
(1) a regular language.
(2) not a deterministic context free language but a context free language.
(3) recursive and is a deterministic context free language.
(4) not recursive.
Answer: 3
25.       Suppose we want to download text documents at the rate of 100 pages per second. Assume that a page consists of an average of 24 lines with 80 characters in each line. What is the required bit rate of the channel?
(1) 192 kbps
(2) 512 kbps
(3) 1.248 Mbps
(4) 1.536 Mbps
Answer: 4
26.       Quadrature Amplitude Modulation means changing both:
(1) Frequency and phase of the carrier.
(2) Frequency and Amplitude of the carrier.
(3) Amplitude and phase of the carrier.
(4) Amplitude and Wavelength of the carrier.
Answer: 3
27.       If a file consisting of 50,000 characters takes 40 seconds to send, then the data rate is ........................
(1) 1 kbps
(2) 1.25 kbps
(3) 2 kbps
(4) 10 kbps
Answer: 4
28.       Match the following:
List - I
(a) Data link layer
(b) Network layer
(c) Transport layer
(d) Presentation layer
List - II
(i) Encryption
(ii) Connection control
(iii) Routing
(iv) Framing
Code :
(a) (b) (c) (d)
(1) (iv) (iii) (i) (ii)
(2) (iii) (iv) (ii) (i)
(3) (iv) (ii) (iii) (i)
(4) (iv) (iii) (ii) (i)
Answer: 4
29.       The address of a class B host is to be split into subnets with a 6 - bit subnet number. What is the maximum number of subnets and maximum number of hosts in each subnet?
(1) 62 subnets and 1022 hosts
(2) 64 subnets and 1024 hosts
(3) 62 subnets and 254 hosts
(4) 64 subnets and 256 hosts
Answer: 1
30.    Which of the following statements are true?
(a) The fragmentation fields in the base header section of IPv4 have moved to the fragmentation extension header in IPv6.
(b) The authentication extension header is new in IPv6.
(c) The record route option is not implemented in IPv6.
Code :
(1) (a) and (b) Only
(2) (b) and (c) Only
(3) (a) and (c) Only
(4) (a), (b) and (c)
Answer: 4