ISRO Computer Science (CSE) 2008 Question Paper & Solutions

Question 1

Which of the following is an illegal array definition?

• A. Type COLONGE : (LIME, PINE, MUSK, MENTHOL); var a : array [COLONGE] of REAL;
• B. var a : array [REAL] of REAL;
• C. var a : array ['A' ... 'Z'] of REAL;
• D. var a : array [BOOLEAN] of REAL;

Answer: B. var a : array [REAL] of REAL;

Explanation: Array index must be integers, enumerators, characters or boolean (discrete types). It cannot be a REAL type.

Question 2

The term Phong associated with

• A. Ray tracing
• B. Shading
• C. Hidden line removal
• D. A game

Answer: B. Shading

Explanation: The term 'Phong' is associated with shading. Phong shading refers to an interpolation technique for surface shading in 3D computer graphics.

Question 3

The subnet mask 255.255.255.192

• A. extends the network portion to 16 bits
• B. extends the network portion to 26 bits
• C. extends the network portion to 36 bits
• D. has no effect on the network portion of an IP address

Answer: B. extends the network portion to 26 bits

Explanation: 255.255.255.192 in binary is 11111111.11111111.11111111.11000000. This corresponds to a /26 prefix length (8+8+8+2 = 26 bits).

Question 4

On a LAN, where are IP datagrams transported?

• A. In the LAN header
• B. In the application field
• C. In the information field of the LAN frame
• D. After the TCP header

Answer: C. In the information field of the LAN frame

Explanation: On a LAN, the IP datagrams are encapsulated and transported in the information (payload) field of the Ethernet/LAN frame.

Question 5

In Ethernet, the source address field in the MAC frame is the ________ address.

• A. original sender's physical
• B. previous station's physical
• C. next destination's physical
• D. original sender's service port

Answer: B. previous station's physical

Explanation: In an Ethernet frame, the source MAC address identifies the sender of that specific frame on the local link (the previous station in the path).

Question 6

Which of the following transmission media is not readily suitable to CSMA operation?

• A. Radio
• B. Optical fibers
• C. Coaxial cable
• D. Twisted pair

Answer: A. Radio

Explanation: Radio is not suitable for standard CSMA/CD because collision detection is difficult (the transmitted signal overpowers the received collision signal). CSMA/CA is used instead.

Question 7

Consider the grammar: S -> ABCc | bc, BA -> AB, Bb -> bb, Ab -> ab, Aa -> aa. Which of the following sentences can be derived by this grammar?

• A. abc
• B. aab
• C. abcc
• D. abbc

Explanation: None of the given options can be derived from the grammar as specified in the question text.

Question 8

The TCP sliding window

• A. can be used to control the flow of information
• B. always occurs when the field value is 0
• C. always occurs when the field value is 1
• D. occurs horizontally

Answer: A. can be used to control the flow of information

Explanation: TCP sliding window is a flow control mechanism used to prevent the sender from overwhelming the receiver.

Question 9

What is the bandwidth of the signal that ranges from 40 kHz 4 MHz

• A. 36 MHz
• B. 360 kHz
• C. 3.96 MHz
• D. 396 MHz

Answer: C. 3.96 MHz

Explanation: Bandwidth = Highest frequency - Lowest frequency = 4 MHz - 0.04 MHz = 3.96 MHz.

Question 10

Which Project 802 standard provides for a collision-free protocol?

• A. 802.2
• B. 802.3
• C. 802.5
• D. 802.6

Answer: C. 802.5

Explanation: IEEE 802.5 (Token Ring) uses a token passing scheme which eliminates collisions, unlike 802.3 (Ethernet) which is contention-based.

Question 11

The Boolean theorem AB + A'C + BC = AB + A'C corresponds to

• A. (A + B).(A' + C).(B + C) = (A + B).(A' + C)
• B. AB + A'C + BC = AB + BC
• C. AB + A'C + BC = (A + B).(A' + C).(B + C)
• D. (A + B).(A' + C).(B + C) = AB + A'C

Answer: A. (A + B).(A' + C).(B + C) = (A + B).(A' + C)

Explanation: This is the dual of the Consensus Theorem. The Consensus Theorem states AB + A'C + BC = AB + A'C. The dual forms are obtained by swapping + and *.

Question 12

In the given network of AND and OR gates f can be written as

• A. X0 X1 X2 ... Xn + X1 X2 ... Xn + X2 X3 ... Xn + ... + Xn
• B. X0 X1 + X2 X3 + ... + Xn-1 Xn
• C. X0 + X1 + X2 + ... + Xn
• D. X0 X1 + X3 ... Xn-1 + X2 X3 + X5 ... Xn-1 + ... + Xn-2 Xn-1 + Xn

Explanation: Based on standard ISRO keys, none of the provided options accurately represent the specific network shown.

Question 13

If N² = (7601)_8 where N is a positive integer, then the value of N is

• A. (241)_5
• B. (143)_6
• C. (165)_7
• D. (39)_16

Answer: B. (143)_6

Explanation: (7601)_8 = 7*8^3 + 6*8^2 + 0*8 + 1 = 3584 + 384 + 1 = 3969. N = $\sqrt{3969}$ = 63. Checking options: (143)_6 = 1*36 + 4*6 + 3 = 36 + 24 + 3 = 63.

Question 14

Assume that each character code consists of 8 bits. The number of characters that can be transmitted per second through an synchronous serial line at 2400 baud rate, and with two stop bits, is :

• A. 109
• B. 216
• C. 218
• D. 219

Answer: C. 218

Explanation: Total bits per character = 1 start bit + 8 data bits + 2 stop bits = 11 bits. Characters per second = 2400 / 11 = 218.18.

Question 15

Four jobs to be executed on a single processor system arrive at time 0 in the order A, B, C, D. Their burst CPU time requirements are 4, 1, 8, 1 time units respectively. The completion time of A under round robin scheduling with time slice of one time unit is

• A. 10
• B. 4
• C. 8
• D. 9

Answer: D. 9

Explanation: Sequence: A(1), B(2), C(3), D(4), A(5), C(6), A(7), C(8), A(9). Job A finishes at time 9.

Question 16

Which one of the following algorithm design techniques is used in finding all pairs of shortest distances in a graph?

• A. Dynamic programming
• B. Backtracking
• C. Greedy
• D. Divide and Conquer

Answer: A. Dynamic programming

Explanation: The Floyd-Warshall algorithm for all-pairs shortest paths uses Dynamic Programming.

Question 17

The address space of 8086 CPU is

• A. 1 Megabyte
• B. 256 Kilobytes
• C. 1 K Megabytes
• D. 64 Kilobytes

Answer: A. 1 Megabyte

Explanation: 8086 has a 20-bit address bus, so it can address 2^20 bytes = 1 MB.

Question 18

More than one word are put in one cache block to

• A. exploit the temporal locality of reference in a program
• B. exploit the spatial locality of reference in a program
• C. reduce the miss penalty
• D. None of these

Answer: B. exploit the spatial locality of reference in a program

Explanation: Fetching a block of multiple words exploits spatial locality because programs tend to access data sequentially.

Question 19

The performance of a pipelined processor suffers if

• A. the pipeline stages have different delays
• B. consecutive instructions are dependent on each other
• C. the pipeline stages share hardware resources
• D. All of the above

Answer: D. All of the above

Explanation: Pipeline hazards include structural hazards (resource sharing), data hazards (dependencies), and bottlenecking from unequal stage delays.

Question 20

If (12x)_3 = (123)_x, then the value of x is

• A. 3
• B. 3 or 4
• C. 2
• D. None of these

Answer: D. None of these

Explanation: LHS base 3 implies digits < 3 (so x < 3). RHS base x implies digits < x (so x > 3). This is a contradiction. Thus no such x exists. (Technically in base 3, digits are 0,1,2. If x is a digit it must be 0,1,2. But RHS base x must be > 3). Wait, (12x) means digits 1, 2, x. For this to be valid in base 3, x must be 0, 1, or 2. If x=2, LHS=(122)_3 = 9+6+2=17. RHS=(123)_2 impossible (digit 3 in base 2). The conditions on x are conflicting.

Question 21

The advantage of MOS devices over bipolar devices is that

• A. it allows higher bit densities and also cost effective
• B. it is easy to fabricate
• C. it is higher-impedance and operational speed
• D. all of these

Answer: D. all of these

Explanation: MOS devices offer high density, lower power, ease of fabrication, and high input impedance.

Question 22

How many 2-input multiplexers are required to construct a 2^10-input multiplexer?

• A. 1023
• B. 31
• C. 10
• D. 127

Answer: A. 1023

Explanation: To build an N-input MUX using 2-input MUXes, we need N-1 MUXes. 2^10 - 1 = 1024 - 1 = 1023.

Question 23

A computer uses 8 digit mantissa and 2 digit exponent. If a = 0.052 and b = 28 E + 11 then b + a - b will

• A. result in an overflow error
• B. result in an underflow error
• C. be 0
• D. be 5.28E + 11

Answer: C. be 0

Explanation: Due to limited precision, adding a very small number 'a' to a very large number 'b' results in 'b' (a is lost). Then subtracting 'b' gives 0. (b+a) = b. b-b = 0.

Question 24

The Boolean expression (A + C)(B' + C) simplifies to

• A. C' + AB'
• B. C(A' + B)
• C. BC + AB'
• D. None of these

Answer: D. None of these

Explanation: (A+C)(B'+C) = AB' + AC + CB' + CC = AB' + C(A+B'+1) = AB' + C. Option (a) is C'+AB', not C+AB'.

Question 25

In the expression A'(A + B) by writing the first term A as A + 0, the expression is best simplified as

• A. A + AB
• B. AB
• C. A
• D. A + B

Answer: B. AB

Explanation: A'(A+B) = A'A + A'B = 0 + A'B = A'B. (Wait, the question asks 'by writing A as A+0' - this seems to imply a specific derivation or perhaps a typo in the question or options. Standard simplification is A'B. The option (b) is AB. The provided key might be mapping to a specific logic. However, mathematically A'(A+B) = A'B).

Question 26

The logic operation of two combinational circuits in Figure-I and Figure-II are

• A. entirely different
• B. identical
• C. complementary
• D. dual

Answer: A. entirely different

Explanation: Figure I implements X' + Y'. Figure II is X'Y'. By De Morgan's, X' + Y' = (XY)'. They are not identical.

Question 27

The output Y of the given circuit

• A. 1
• B. 0
• C. X
• D. X'

Answer: B. 0

Explanation: The XOR chain logic. First XOR: X XOR 0 = X. Second: X XOR 1 = X'. Third: X' XOR X = 1. Fourth: 1 XOR X? Wait, tracing carefully. Input 0 -> XOR1 -> X. XOR2(X, 1) -> X'. XOR3(X', X) -> 1. XOR4(1, X) -> X'. The key says 0. Let's re-evaluate based on diagram visually. If inputs are provided differently... Assuming standard cascade. If inputs are A and B to XOR. Fig shows inputs are chained.

Question 28

Which of the following is not a valid rule of XOR?

• A. 0 XOR 0 = 0
• B. 1 XOR 1 = 1
• C. 1 XOR 0 = 1
• D. B XOR B = 0

Answer: B. 1 XOR 1 = 1

Explanation: 1 XOR 1 = 0. So 1 XOR 1 = 1 is invalid.

Question 29

The number of distinct simple graphs with up to three nodes is

• A. 15
• B. 10
• C. 7
• D. 9

Answer: C. 7

Explanation: For n=1: 1 graph. n=2: 2 graphs (0 or 1 edge). n=3: 4 graphs (0, 1, 2, 3 edges). Total = 1 + 2 + 4 = 7.

Question 30

The maximum number of edges in a n-node undirected graph without self loops is

• A. n²
• B. n(n-1)/2
• C. n - 1
• D. (n+1)(n)/2

Answer: B. n(n-1)/2

Explanation: This is a complete graph Kn.

Question 31

If the two matrices [[1, 0, 1], [0, x, 1], [0, 1, x]] and [[x, 1, 0], [x, 0, 1], [0, x, 1]] have the same determinant, then the value of x is

• A. 1/2
• B. $\sqrt{2}$
• C. +- 1/2
• D. +- 1/$\sqrt{2}$

Answer: A. 1/2

Explanation: Det1 = 1(x² - 1). Det2 = x(-x) - 1(x) = -x² - x. x² - 1 = -x² - x. 2x^2 + x - 1 = 0. (2x-1)(x+1) = 0. x = 1/2 or -1.

Question 32

A network 198.78.41.0 is a

• A. Class A network
• B. Class B network
• C. Class C network
• D. Class D network

Answer: C. Class C network

Explanation: First octet 198 falls in the range 192-223, which is Class C.

Question 33

The join operation can be defined as

• A. a cartesian product of two relations followed by a selection
• B. a cartesian product of two relations
• C. a union of two relations followed by cartesian product of the two relations
• D. a union of two relations

Answer: A. a cartesian product of two relations followed by a selection

Explanation: Join allows combining related tuples from two relations, conceptually equivalent to cross product followed by selection on the join condition.

Question 34

If a square matrix A satisfies A^T A = I, then the matrix A is

• A. Idempotent
• B. Symmetric
• C. Orthogonal
• D. Hermitian

Answer: C. Orthogonal

Explanation: A matrix is orthogonal if A^T = A^-1, or A^T A = I.

Question 35

Embedded pointer provides

• A. A secondary access path
• B. A physical record key
• C. An inverted index
• D. A primary key

Answer: A. A secondary access path

Explanation: Embedded pointers are used to link records, providing secondary access paths (e.g., in linked lists within files).

Question 36

An interrupt in which the external device supplies its address as well as the interrupt requests is known as

• A. vectored interrupt
• B. maskable interrupt
• C. non maskable interrupt
• D. designated interrupt

Answer: A. vectored interrupt

Explanation: In a vectored interrupt, the device sends the interrupt vector address to the CPU.

Question 37

The ability to temporarily halt the CPU and use this time to send information on buses is called

• A. direct memory access
• B. vectoring the interrupt
• C. polling
• D. cycle stealing

Answer: D. cycle stealing

Explanation: Cycle stealing allows a DMA controller to access memory by temporarily suspending the CPU's memory access for a cycle.

Question 38

Relative to the program translated by a compiler, the same program when interpreted runs

• A. Faster
• B. Slower
• C. At the same speed
• D. May be faster or slower

Answer: B. Slower

Explanation: Interpreters decode and execute line-by-line at runtime, which is slower than executing pre-compiled machine code.

Question 39

Consider the following Assembly language program: MVIA 30H; ACI 30H; XRA A; POP H. After the execution of the above program, the contents of the accumulator will be

• A. 30 H
• B. 60 H
• C. 00 H
• D. contents of stack

Answer: C. 00 H

Explanation: XRA A (XOR Accumulator with itself) always results in 00H.

Question 40

Consider the following C function : int f(int n) { static int i = 1; if (n >= 5) return n; n = n + i; i++; return f(n); } The value returned by f(1) is

• A. 5
• B. 6
• C. 7
• D. 8

Answer: C. 7

Explanation: f(1): i=1, n=1+1=2, i=2, call f(2). f(2): i=2, n=2+2=4, i=3, call f(4). f(4): i=3, n=4+3=7, i=4, call f(7). f(7): n>=5, return 7.

Question 41

In a resident-OS computer, which of the following systems must reside in the main memory under all situations?

• A. Assembler
• B. Linker
• C. Loader
• D. Compiler

Answer: C. Loader

Explanation: The Loader (or part of the OS kernel responsible for loading) must be in memory to load other programs.

Question 42

Which of the following architecture is/are not suitable for releasing SIMD?

• A. Vector processor
• B. Array processor
• C. Von Neumann
• D. All of the above

Answer: C. Von Neumann

Explanation: Standard Von Neumann architecture is SISD (Single Instruction Single Data), not SIMD.

Question 43

What is printed as a result of executing the code segment? for(int k=0; k<20; k=k+2) { if(k%3 == 1) print(k + " "); }

• A. 4 16
• B. 4 10 16
• C. 0 6 12 18
• D. 1 4 7 10 13 16 19

Answer: B. 4 10 16

Explanation: k takes values 0, 2, 4, 6, 8, 10, 12, 14, 16, 18. k%3==1 checks: 0(0), 2(2), 4(1)-Print, 6(0), 8(2), 10(1)-Print, 12(0), 14(2), 16(1)-Print, 18(0). Prints: 4 10 16.

Question 44

The device which is used to connect a peripheral to bus is known as

• A. control register
• B. interface
• C. communication protocol
• D. none of these

Answer: B. interface

Explanation: An I/O Interface connects the peripheral device to the system bus.

Question 45

The TRAP is one of the interrupts available in INTEL 8085. Which one of the following statements is true of TRAP?

• A. it is level triggered
• B. it is negative edge triggered
• C. it is +ve edge triggered
• D. it is both +ve and -ve edges triggered

Answer: D. it is both +ve and -ve edges triggered

Explanation: Actually, TRAP is both edge and level triggered (Edge to recognize, level to sustain). The standard ISRO answer usually marks it as edge/level or specific triggers.

Question 46

Raid configuration of the disks are used to provide

• A. Fault-tolerance
• B. High speed
• C. High data density
• D. Option (a) and (b)

Answer: D. Option (a) and (b)

Explanation: RAID provides fault tolerance (redundancy) and/or high speed (striping).

Question 47

Which of the following need not necessarily be saved on a context switch between processes?

• A. General purpose registers
• B. Translation look-aside buffer
• C. Program counter
• D. All of the above

Answer: B. Translation look-aside buffer

Explanation: TLB contents are usually flushed or tagged, but not 'saved' and 'restored' like registers. They are a cache.

Question 48

Which of the following is termed as minimum error code

• A. Binary code
• B. Gray code
• C. Excess 3 code
• D. Octal code

Answer: B. Gray code

Explanation: Gray code changes by only one bit between consecutive numbers, minimizing error in transitions.

Question 49

The total time to prepare a disk drive mechanism for a block of data to be read from it is

• A. seek time
• B. latency
• C. latency plus seek time
• D. transmission time

Answer: C. latency plus seek time

Explanation: Access time = Seek Time (move arm) + Rotational Latency (spin to sector).

Question 50

Feedback queues

• A. are very simple to implement
• B. dispatch tasks according to execution characteristics
• C. are used to favour real time tasks
• D. require manual intervention to implement properly

Answer: B. dispatch tasks according to execution characteristics

Explanation: Multilevel feedback queues allow processes to move between queues based on their CPU burst behavior.

Question 51

With Round-Robin CPU scheduling in a time shared system

• A. using very large time slices (quantas) degenerates into First-Come First Served (FCFS) algorithms.
• B. using extremely small time slices improves performance
• C. using very small time slices degenerates into Last-in First-Out (LIFO) algorithm.
• D. using medium sized times slices leads to shortest Request time First (SRTF) algorithm

Answer: A. using very large time slices (quantas) degenerates into First-Come First Served (FCFS) algorithms.

Explanation: If the time quantum is larger than the burst time of all processes, RR becomes FCFS.

Question 52

Dynamic address translation

• A. is part of the operating system paging algorithm
• B. is useless when swapping is used
• C. is the hardware necessary to implement paging
• D. storage pages at a specific location on disk

Answer: C. is the hardware necessary to implement paging

Explanation: Hardware (MMU) is required to translate logical addresses to physical addresses dynamically.

Question 53

Thrashing

• A. always occurs on large computers
• B. is a natural consequence of virtual memory systems
• C. can always be avoided by swapping
• D. can be caused by poor paging algorithms

Answer: D. can be caused by poor paging algorithms

Explanation: Thrashing is excessive paging caused by lack of frames or poor replacement algorithms/locality.

Question 54

What is the name of the operating system that reads and reacts in terms of operating system?

• A. Batch system
• B. Quick response time
• C. Real time system
• D. Time sharing system

Answer: C. Real time system

Explanation: Real time systems must react to inputs within a specific time constraint.

Question 55

The Memory Address Register

• A. is a hardware memory device which denotes the location of the current instruction being executed.
• B. is a group of electrical circuit, that performs the intent of instructions fetched from memory
• C. contains the address of the memory location that is to be read from or stored into
• D. contains a copy of the designated memory location specified by the MAR after a "read"

Answer: C. contains the address of the memory location that is to be read from or stored into

Explanation: MAR holds the address of the memory location to be accessed.

Question 56

Which of the following is an example of spooled device?

• A. A line printer used to print the output of a number of jobs
• B. A terminal used to enter input data to a running program
• C. A secondary storage device in a virtual memory system
• D. A graphic display device

Answer: A. A line printer used to print the output of a number of jobs

Explanation: Printers are classic spooled devices where jobs are queued on disk.

Question 57

Dirty bit for a page in a page table

• A. helps avoid unnecessary writes on a paging device
• B. helps maintain LRU information
• C. allows only read on a page
• D. None of the above

Answer: A. helps avoid unnecessary writes on a paging device

Explanation: Dirty bit indicates if a page has been modified. If not set, the page doesn't need to be written back to disk.

Question 58

Check pointing a job

• A. allows it to be completed successfully
• B. allows it to continue executing later
• C. prepares it for finishing
• D. occurs only when there is an error in it

Answer: B. allows it to continue executing later

Explanation: Checkpointing saves the state of a process so it can be resumed.

Question 59

A public key encryption system

• A. allows anyone to decode the transmissions
• B. allows only the correct sender to decode the data
• C. allows only the correct receiver to decode the data
• D. does not encode the data before transmitting it

Answer: C. allows only the correct receiver to decode the data

Explanation: In public key encryption, data encrypted with the public key can only be decrypted by the private key holder (receiver).

Question 60

Overlaying

• A. requires use of a loader
• B. allows larger programs, but requires more effort
• C. is most used on large computers
• D. is transparent to the user

Answer: B. allows larger programs, but requires more effort

Explanation: Overlays allow running programs larger than physical memory but require manual programming effort.

Question 61

A critical section is a program segment

• A. which should run in a certain amount of time.
• B. which avoids deadlocks.
• C. where shared resources are accessed.
• D. which must be enclosed by a pair of semaphore operations, P and U.

Answer: C. where shared resources are accessed.

Explanation: A critical section is code that accesses shared resources and must not be executed concurrently by multiple processes.

Question 62

In which of the following four necessary conditions for deadlock processes claim exclusive control of the resources they require?

• A. no preemption
• B. mutual exclusion
• C. circular wait
• D. hold and wait

Answer: B. mutual exclusion

Explanation: Mutual exclusion ensures that at least one resource is held in a non-sharable mode.

Question 63

Fork is

• A. the creation of a new job
• B. the dispatching of a task
• C. increasing the priority of a task
• D. the creation of a new process

Answer: D. the creation of a new process

Explanation: Fork system call creates a new process (child).

Question 64

Which of the following need not necessarily be saved on a Context Switch between processes?

• A. General purpose register
• B. Translation look-aside buffer
• C. Program counter
• D. Stack pointer

Answer: B. Translation look-aside buffer

Explanation: Same as Q47. TLB is not saved/restored, it is flushed.

Question 65

Consider a logical address space of 8 pages of 1024 words mapped into memory of 32 frames. How many bits are there in the logical address?

• A. 13 bits
• B. 15 bits
• C. 14 bits
• D. 12 bits

Answer: A. 13 bits

Explanation: 8 pages = 2^3. 1024 words = 2^10. Total logical address bits = 3 + 10 = 13 bits.

Question 66

The performance of Round Robin algorithm depends heavily on

• A. size of the process
• B. the I/O bursts of the process
• C. the CPU bursts of the process
• D. the size of the time quantum

Answer: D. the size of the time quantum

Explanation: The time quantum determines response time and overhead.

Question 67

The page replacement algorithm which gives the lowest page fault rate is

• A. LRU
• B. FIFO
• C. Optimal page replacement
• D. Second change algorithm

Answer: C. Optimal page replacement

Explanation: Optimal algorithm (replacing page that will not be used for longest time) is theoretically the best.

Question 68

Which of the following class of statement usually produces no executable code when compiled?

• A. declaration
• B. assignment statements
• C. input and output statements
• D. structural statements

Answer: A. declaration

Explanation: Declarations tell the compiler about types and memory needs but don't usually generate executable machine instructions.

Question 69

What is the value of F(4) using the following procedure : Function F(K : integer) integer; begin if (K < 3) then F := K else F := F(k - 1) * F(k - 2) + F(k - 3) end

• A. 5
• B. 6
• C. 7
• D. 8

Answer: A. 5

Explanation: F(0)=0, F(1)=1, F(2)=2. F(3) = F(2)*F(1)+F(0) = 2*1+0 = 2. F(4) = F(3)*F(2)+F(1) = 2*2+1 = 5.

Question 70

Stack A has the entries a, b, c (with a on top). Stack B is empty. An entry popped out of stack A can be printed immediately or pushed to stack B. An entry popped out of the stack B can be only printed. In this arrangement, which of the following permutations of a, b, c are not possible?

• A. b a c
• B. b c a
• C. c a b
• D. a b c

Answer: C. c a b

Explanation: With a stack, we cannot get 'c a b' because to pop 'c', 'a' and 'b' must be popped first. If 'b' is printed before 'a', 'a' is stuck in B until 'c' is handled? If 'c' is first, 'b' and 'a' are in stack B (b on top of a). So we must pop 'b' then 'a'. Output would be 'c b a'.

Question 71

The time required to search an element in a linked list of length n is

• A. O(log_2 n)
• B. O(n)
• C. O(1)
• D. O(n²)

Answer: B. O(n)

Explanation: Linked lists require sequential access traversal.

Question 72

Which of the following operations is performed more efficiently by doubly linked list then by linear linked list?

• A. Deleting a node whose location is given
• B. Searching an unsorted list for a given item
• C. Inserting a node after the node with a given location
• D. Traversing the list to process each node

Answer: A. Deleting a node whose location is given

Explanation: In a doubly linked list, we can access the previous node directly to update links. In a singly list, we need to traverse from head.

Question 73

We can make a class abstract by

• A. Declaring it abstract using the virtual keyword
• B. Making at least one member function as virtual function
• C. Making at least one member function as pure virtual function
• D. Making all member function const.

Answer: C. Making at least one member function as pure virtual function

Explanation: In C++, a class with at least one pure virtual function is abstract.

Question 74

A Steiner patch is

• A. Biquadratic Bezeir patch
• B. Bicubic patch
• C. Circular patch only
• D. Bilinear Bezier patch

Answer: A. Biquadratic Bezeir patch

Explanation: A Steiner patch is a specific type of surface patch, often associated with biquadratic Bezier.

Question 75

A complete binary tree with the property that the value at each node is at least as large as the values at its children is known as

• A. Binary search tree
• B. AVL tree
• C. Completely balanced tree
• D. Heap

Answer: D. Heap

Explanation: This is the max-heap property.

Question 76

The minimum number of fields with each node of doubly linked lists is

• A. 1
• B. 2
• C. 3
• D. 4

Answer: C. 3

Explanation: Data, Next Pointer, Previous Pointer.

Question 77

How many comparisons are needed to sort an array of length 5 if a straight selection sort is used and array is already in the opposite order?

• A. 1
• B. 10
• C. 15
• D. 20

Answer: B. 10

Explanation: Selection sort comparisons are n(n-1)/2 regardless of order. 5*4/2 = 10.

Question 78

Consider the graph shown in the figure below. Which of the following is a valid strong component?

• A. a, c, d
• B. a, b, d
• C. b, c, d
• D. a, b, c

Answer: D. a, b, c

Explanation: Looking at standard examples (often a cycle a->b->c->a), {a,b,c} forms a Strongly Connected Component.

Question 79

Repeated execution of simple computation may cause compounding of

• A. round-off errors
• B. syntax errors
• C. run-time errors
• D. logic errors

Answer: A. round-off errors

Explanation: Floating point round-off errors accumulate with repeated calculations.

Question 80

In C, what is the effect of a negative number in a field width specifier?

• A. the values are displayed right justified
• B. the values are displayed centered
• C. the values are displayed left justified
• D. the values are displayed as negative numbers

Answer: C. the values are displayed left justified

Explanation: A negative width (e.g. %-10d) left-justifies the output.