UGC NET CS 2007 June-Paper-2

 Question 1
The following deterministic finite automata recognizes : A Set of all strings containing ‘ab’ B Set of all strings containing ‘aab’ C Set of all strings ending in ‘abab’ D None of the above
Theory-of-Computation       Finite-Automata
Question 1 Explanation:
There is no final state in the given deterministic finite automata so it can't accept any string. Hence the answer is option(D)
 Question 2
Depth ion travels of the following directed graph is : A A B C D E F B A B D E F C C A C E B D F D None of the above
Data-Structures       Graphs-and-Tree
Question 2 Explanation:
To find depth ion traverse using DFS.
Option-A: It is ruled out because we can’t move after C to D. It is violating DFS property.
Option-B: It is following actual DFS structure. Option-C: It is ruled out because after visiting E we can’t visit B again. It is violating DFS properties.
 Question 3
The maximum number of nodes in a binary tree of depth 10 :
 A 1024 B 210 - 1 C 1000 D None of the above
Data-Structures       Binary-Trees
Question 3 Explanation:
→ The depth of binary tree starts from 0 but not 1.
→ To find maximum number of nodes in a binary tree of depth using formula is
= 2h+1 -1
= 211 -1
= 2048-1
= 2047 Question 4
The regular expression given below describes : r=(1+01)* (0+λ)
 A Set of all string not containing ‘11’ B Set of all string not containing ‘00’ C Set of all string containing ‘01’ D Set of all string ending in ‘0’
Theory-of-Computation       Regular-Expression
Question 4 Explanation:
L= { λ, 0, 1λ, 01λ, 10, 010, 110, .............}
According to the language L generated by given regular expression
Option(A) is incorrect because L contains 110.
Option(B) is correct because no string is containing 00
Option(C) is incorrect because not all strings in L are containing 01 example 0 in L does not contain 01.
Option(D) is incorrect because L contains 1λ is there in L which is not ending with 0.
Hence correct answer is option (B)
 Question 5
Which of the following language is regular :
 A L = { an bn| n ≥ 1 } B L = { an bm cn dm|n, m ≥ 1 } C L = { an bm|n, m ≥ 1 } D L = { an bm cn|n, m ≥ 1 }
Theory-of-Computation       Regular-Language
Question 5 Explanation:
Language generated in Option (A) requires a memory element to count equal number of b's after a. And since regular languages are accepted by finite automata which does not have a memory element. Hence Option (A) language is not Regular.
Language generated in Option (B) requires a memory element and a read write head which can move in both the directions to count equal number of a's and c's , and b's and d's. And since regular languages are accepted by finite automata which does not have a memory element and a read write head which can move in both the directions. Hence Option (A) language is not Regular.
Language generated in Option (C) is regular because number of a's and b's is not necessarily need to be same which means no memory element is required. Hence it is a regular language.
Language generated in Option (D) requires a memory element to count equal number of c's after a. And since regular languages are accepted by finite automata which does not have a memory element. Hence Option (A) language is not Regular. The language generated here is context free language which can be accepted by pushdown automata.
 Question 6
2’s complement of -100 is :
 A 00011100 B 10011101 C 10011100 D 11100100
Digital-Logic-Design       Number-Systems
Question 6 Explanation: Question 7
Which of the following expression remove hazard form : xy+zx’ ?
 A xy+zx’ B xy+zx’ C xy+zx’+yz D xy+zx’+wz
Question 7 Explanation:
→ A static hazard occurs if a circuit produces incorrect output value momentarily before stabilizing to its correct value.
→ Generally Hazard occurs due to different delays in different paths of the circuit.
→ In the expression xy +zx’ the variable x is in true form in one term(xy) and in complement in other term(zx').
→ Delay occurs due to the presence of NOT gate.
If input xyz=111 then output is 1.
If input xyz=011 then output stays momentarily in state 0 then settles in state 1.
→ Adding the term yz(select y from xy and z from zx') eliminates the hazard.
 Question 8
How many 1’s are present in the binary representation of 15*256 + 5*16 + 3 :
 A 8 B 9 C 10 D 11
Digital-Logic-Design       Number-Systems
Question 8 Explanation:
Step-1: The precedence to given decimal number is (15*256) + (5*16) + 3
Step-2: 3840+80+3=(3923)10
Step-3: Convert decimal number into binary
(3923)10 = (‭111101010011‬ )2
Step-4: Total number of 1’s are 8.
 Question 9
If A⊕B=C , then :
 A A ⊕ C = B B B ⊕ C = A C A ⊕ B ⊕ C = 1 D A ⊕ B ⊕ C = 0 E None of the above
Digital-Logic-Design       Boolean-Expression
Question 9 Explanation:
Given that A⊕B=C
1) A⊕B⊕ C = C⊕C
A⊕B⊕ C = 0 (Since C⊕C =0)
option D is correct.
So option C is not correct.
2) From step 1, we know that A⊕B⊕ C = 0
A⊕B⊕ C ⊕ B= 0 ⊕ B
A ⊕ C = B (Since B ⊕ B= 0)
So option A is correct.
3) From step 1, we know that A⊕B⊕ C = 0
A⊕B⊕ C ⊕ A= 0 ⊕ A
B ⊕ C = A (Since A ⊕ A =0)
So option B is also correct.
 Question 10
What is the maximum counting speed of a 4-bit binary counter which is composed of Flip-Flop with a propagation delay of 25ns ?
 A 1MHz B 10MHz C 100MHz D 4MHz
Digital-Logic-Design       Sequential-Circuits
Question 10 Explanation:
Question is about frequency of the counter.
Frequency = 1/ Time
Binary counter is ripple counter where the output one flip flop is clock input to next flip flop.
So, maximum delay(time)= 4*25ns = 100 ns.
frequency= 1/100 ns
= 10 MHz.
 Question 11
The following loop in ‘C’ :
int i=0;
while (i++ < 0)
i-- ;
 A will terminate B will go into an infinite loop C will give compilation error D will never be executed
Programming       Control-Statement
Question 11 Explanation:
#include
void main()
{
int i=0;
while(i++ < 0)
{
i--;
printf("%d",i);
}
}
/* It will terminate null value */
 Question 12
In case of right shift bitwise operator in ‘C’ language, after shifting n bits, the leftmost n bits :
 A are always filled with zeros B are always filled with ones C are filled with zeros or ones and is machine dependent D none of the above
Question 12 Explanation:
In case of right shift bitwise operator in ‘C’ language, after shifting n bits, the leftmost n bits are filled with zeros or ones and is machine dependent.
Example:
Input: positive number→ It will filled with zeros
Input: Negative number → it will filled with ones
Option-C is more appropriate answer.
 Question 13
What keyboard in class specification helps to hide data :
 A Public B Private C Static D Void
Programming-in-c++       Properties
Question 13 Explanation:
→ Private access specifier will helps to hide data.
→ The private access modifier is accessible only within class.
 Question 14
What is the output of the following ‘C’ program ?
main( )
{
printf (“%x”, -1>>4);
}
 A ffff B Offf C OOOO D fffO
Programming       Operator
Question 14 Explanation: Question 15
Runtime polymorphism can be achieved by :
 A Accessing virtual function through the pointer of the base class B Accessing virtual function through the object C The derived class D None of these
Programming-in-c++       Properties
Question 15 Explanation:
Runtime polymorphism can be achieved by accessing virtual function through the pointer of the base class.
 Question 16
Which of the following statements is wrong ?
 A 2-phase Locking Protocols suffer from dead locks. B Time - Stamp Protocols suffer from more aborts. C Timestamp Protocols suffer from cascading rollback where as 2-phase locking Protocol donot. D None of these
Database-Management-System       Transactions
Question 16 Explanation:
2-Phase locking: It provides a serializable schedule but does not provides a deadlock free serializable schedule. Deadlock might occur using this concurrency control mechanism.
Time Stamp Protocol: It suffers more aborts in comparison of other concurrency control protocols because of allowing the execution of the transactions based upon their time stamp ordering. A transaction with higher timestamp is allowed to execute otherwise if a transaction with lower timestamp requests for execution then in that case that transaction will be aborted.
 Question 17
A recursive foreign key is a :
 A references a relation. B references a table. C references its own relation D references a foreign key.
Database-Management-System       Keys
Question 17 Explanation:
→ A recursive foreign key is a references its own relation.
→ Recursive foreign key is a foreign key which refers back to the primary key in the same table where child and parent table are same.
 Question 18
A subclass having more than one super class is called :
 A Category B Classification C Combination D Partial Participation
Programming-in-c++       Properties
Question 18 Explanation:
A subclass having more than one super class is called category.
 Question 19
A Relation R = {A,B,C,D,E,F} is given with following set of functional dependencies
F={A →B, AD→C, B→F, A→ E}.
Which of the following is Candidate Key ?
 A A B AC C AD D None of these
Database-Management-System       Functional-Dependency
Question 19 Explanation: Question 20
Which statement is false regarding data Independence :
 A Hierarchical data model suffers from data Independence. B Network model suffers from data Independence. C Relational model suffers only from logical data Independence. D Relational model suffers only from physical data Independence.
Question 20 Explanation:
TRUE: Hierarchical data model suffers from data independence
TRUE: Network model suffers from data independence
FLASE: Relational model suffers only from logical data independence.
Note: Relational model means tabular representation of the database and since tabular is in 1NF but for remaining normal forms there is some dependency problem exist not independency exist
TRUE: Relational model suffers only from physical data independence
 Question 21
The time required to find shortest path in a graph with n vertices and e edges is :
 A O(e) B O(n) C O(e2) D O(n2)
Algorithms       Greedy-approach
Question 21 Explanation:
→ We can use dijkstra’s algorithm to find shortest path in a graph with n vertices and e edges is O(ElogV).
→ We know that E ≤ V2 if graph is complete and time complexity is O(n2)
 Question 22
Pre order is also known as :
 A Depth first order B Breadth first order C Topological order D Linear order
Data-Structures       Graphs-and-Tree
Question 22 Explanation:
→ Pre order is also known as depth first order.
→ A depth-first order is defined to be the reverse of the order in which we last visit the nodes of the control graph when we create the Depth first spanning tree(DFST).
 Question 23
The equivalent postfix express for d/(e+f) + b*c is :
 A defbc/+ + B def+/bc+* C def+/bc*+ D None of these
Data-Structures       Queues-and-Stacks
Question 23 Explanation: Question 24
Which algorithm has some average, worst case and best case time :
 A Binary search B Maximum of n numbers C Quick sort D Fibonacci search
Algorithms       Time-Complexity
Question 24 Explanation: Question 25
Application of data structure is queue is :
 A Level wise printing of tree. B Implementation of priority queues. C Function call implementation D Depth first search in a graph
Data-Structures       Queues-and-Stacks
Question 25 Explanation:
Queue applications:
1. CPU scheduling
2. Disk Scheduling
3. synchronization(IO Buffers, pipes, file IO, etc.)
4. Breadth First search
5. Implementation of priority queues.
 Question 26
In case of Bus/Tree topology signal balancing issue is overcome by :
 A Strong Transmitter B Polling C Segmentation D Modulation
Computer-Networks       Topologies
Question 26 Explanation:
In case of Bus/Tree topology signal balancing issue is overcome by segmentation.
 Question 27
Which of the following techniques are used to control data flow ?
1.Windowing
2.Routing
3.RPCs
4.Buffering
 A 1,4 B 2,3,4 C 1,3,4 D 1,2,3,4
Computer-Networks       Routing
Question 27 Explanation:
Windowing and buffering are used to control data flow.
 Question 28
TDM is __________ .
 A A primary/secondary type protocol B A peer/peer protocol C A Non-priority peer/peer protocol D A priority type protocol
Question 28 Explanation:
TDM:
1. TDM stands time division multiplexing.
2. Cross talk like problem not occurs in TDM.
3. TDM requires channel synchronization
4. TDM has greater noise immunity.
→ TDM is a non-priority peer/peer protocol.
 Question 29
What services does the Internet Layer provide ?
1. Quality of service
2. Routing
4. Connection oriented delivery
5. Framing bits
 A 1,2,3 B 2,3,4 C 1,3,4,5 D 2,3,4,5
Computer-Networks       Routing
Question 29 Explanation:
→ We can ruled out statement 4 and 5 because internet layer is connectionless delivery and framing bits are used in data link layer but not in internet layer.
→ Internet layer provides
1. Quality of service
2. Routing
 Question 30
Which of the following protocols is used to prevent looping ?
 A OSPF B Spanning tree C SRB D Fragment free switching
Computer-Networks       Hardware-and-various-devices-in-networking
Question 30 Explanation:
Spanning tree is used to prevent looping because it has maximum n-1 edges.
 Question 31
The parsing technique that avoids backtracking is :
 A Top - down parsing B Recursive - descent parsing C Predicative D Syntax tree
Compiler-Design       Parsers
Question 31 Explanation:
→ Top-down parsers are predictive parsers, because next tokens are predicted.
→ Predictive parser is a recursive descent parser, which has the capability to predict which production is to be used to replace the input string.
→ The predictive parser does not suffer from backtracking.
→ Predictive parsing uses a stack and a parsing table to parse the input and generate a parse tree.
 Question 32
A Top down Parser generates :
 A Rightmost derivation. B Rightmost derivation, in reverse. C Leftmost derivation. D Leftmost derivation in reverse.
Compiler-Design       Parsers
Question 32 Explanation:
→ A Top down Parser generates leftmost derivation.
→ A bottom up parser generates rightmost derivation, in reverse.
 Question 33
In an absolute loading scheme, which loader function is accomplished by programmer ?
 A Allocation B Linking C Rellocation D Both (A) and (B)
Question 33 Explanation:
→ Loader loads the executable code into memory, program and data stack are created, register gets initialized.
→ Re-allocation is an absolute loading scheme which loader function is accomplished by assembler
 Question 34
Symbol table can be used for :
 A Checking type compatibility B Suppressing duplication of error message C Storage allocation D All of these above
Compiler-Design       Symbol-Table
Question 34 Explanation:
Symbol table can be used for
1. Checking type compatibility
2. Suppressing duplication of error message
3. Storage allocation
 Question 35
Moving process from main memory to disk is called :
 A Caching B Termination C Swapping D Interruption
Operating-Systems       Memory-Management
Question 35 Explanation:
→ Page making process from main memory to disk is called swapping.
→ Swapping is a mechanism in which a process can be swapped/moved temporarily out of main memory to a backing store , and then brought back into memory for continued execution.
 Question 36
Part of a program where the shared memory is accessed and which should be executed indivisibly, is called :
 A Semaphores B Directory C Critical section D Mutual exclusion
Operating-Systems       Memory-Management
Question 36 Explanation:
→ Consider a system consisting of n processes {p0,p1,...,pn-1}. Each process has a segment of code, called a critical section, in which the process my changing changing common variable,updating a table, writing a file, and so on.
→ Part of a program where the shared memory is accessed and which should be executed indivisibly, is called critical section.
 Question 37
Windows is a __________ operating system :
 A Non-preemptive B Preemptive C Multi-user D Real time
Operating-Systems       Windows-Operating-System
Question 37 Explanation:
Among all possible options, Option-C is more appropriate. Windows is a multi-user operating system.
 Question 38
The “nice” command is used in Unix :
 A to decrease the priority of a process. B to increase the priority of a process. C to get the highest priority. D nothing to do with the priorities. E None of the above
Operating-Systems       UNIX-Operating-System
Question 38 Explanation:
→ The “nice” command is used in Unix to decrease/increase the priority of a process.
→ A process with a lower niceness value is given higher priority and more CPU time. A process with a higher niceness value (a "nicer" process) is given a lower priority and less CPU time, freeing up resources for processes that are more demanding.
 Question 39
Which page replacement policy suffers from Belady’s anomaly ?
 A LRV B LFU C FIFO D OPTIMAL
Operating-Systems       Page-Replacement-algorithm
Question 39 Explanation:
FIFO page replacement policy suffers from Belady’s anomaly.
 Question 40
Cache memory is :
 A High-Speed Register B Low-Speed RAM C Non-Volatile RAM D High-speed RAM
Computer-Organization       Cache
Question 40 Explanation:
Option-A is ruled out because it is not register. Registers are more faster than cache memory. Option-B and D is ruled out because it is not a type RAM.
Option-C is more appropriate answer
 Question 41
Which of the following combination is preferred with respect to cohesion and coupling :
 A low and low B low and high C high and low D high and high
Software-Engineering       Coupling-and-Cohesion
Question 41 Explanation:
→ Cohesion is a measure of internal strength within a module, whereas coupling is a measure of inter dependency among the modules.
→ So in the context of modular software design there should be high cohesion and low coupling.
 Question 42
Difference between flowchart and data-flow diagram is :
 A there is no difference B usage in high level design and low level design C control flow and data flow D used in application programs and system programs
Question 42 Explanation: Question 43
Match the following : Which of the following is true :
 A (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i) B (a)-(i), (b)-(ii), (c)-(iv), (d)-(iii) C (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii) D None of the above
Software-Engineering       Software-testing
Question 43 Explanation: Question 44
Problems with waterfall model are :
1. Real projects rarely follow this model proposes
2. It is often difficult for the customer
3. Working model is available only in the end
4. Developers are delayed unnecessarily
Which of the following is true :
 A 1 and 4 only B 2 and 3 only C 1, 2 and 3 only D 1, 2, 3 and 4
Software-Engineering       Waterfall-model
Question 44 Explanation:
Problems with waterfall model are
1. Real projects rarely follow this model proposes
2. It is often difficult for the customer
3. Working model is available only in the end
4. Developers are delayed unnecessarily
 Question 45
Which one of the following is a object-oriented approaches :
 A The Booch method B The Rumbaugh method C The coad and Yomdon method D All of the above
Question 45 Explanation:
Object-oriented approaches
1.The Rumbaugh method
2. The Booch method
3. The Coad-Yourdon method
4. The Shlaer-Mellor method
 Question 46
Which technical concept sets cellular apart from all preceding mobile/radio systems ?
 A FM-Transmission B Duplex Functionality C Frequency Reuse D TDMA Technology
Question 46 Explanation:
→ TDMA sets cellular apart from all preceding mobile/radio systems.
TDM:
1. TDM stands time division multiplexing.
2. Cross talk like problem not occurs in TDM.
3. TDM requires channel synchronization
4. TDM has greater noise immunity.
→ TDM is a non-priority peer/peer protocol.
 Question 47
Wireless interconnection to the PSTN are also known as :
 A Localities B CLECs C POPs D IXCs
Question 47 Explanation:
Wireless interconnection to the PSTN(Public Switched Telephone Network) are also known as POP(Point of Presence).
 Question 48
Dimensional modeling in Data Mining refers to :
 A view and interrogate data B define structures and store data C retrieve information only D none of these
Question 48 Explanation:
→ Dimensional modeling in Data Mining refers to view and interrogate data.
→ Dimensional modeling is based on two concepts called facts and dimensions.
 Question 49
The U-NII (Unlicensed National Information Infrastructure) band operates at the<__________ frequency :
 A 2.4 GHz B 33 MHz C 5 GHz D 16 GHz
Question 49 Explanation:
The Unlicensed National Information Infrastructure (U-NII) radio band is part of the radio frequency spectrum used by IEEE 802.11a devices and by many wireless ISPs. It operates over following ranges: Question 50
Which digital radio technology employs an N = 1 frequency-reuse plan ?
 A GSM B TDMA C D AMPS D CDMA
Question 50 Explanation:
Cellular CDMA systems can use N=1(it means the same frequency is used in all cells)
There are 50 questions to complete.
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