BCS Technical Cadre (CSE) October 2025 – 49th BCS Written (Special) (BPSC) question & solution

MCQ (96)

1. A router processes packets @1 Gbps; if 10 packets (1200 bytes each) arrive at once, queuing delay for the 10th packet (in µs) is:
   1. a) 96
   2. b) 86.4
   3. c) 115.2
   4. d) 120
2. OSI ___ Layer establishes, manages & terminates logical connections between applications.
   1. a) Transport
   2. b) Network
   3. c) Session
   4. d) Data link
3. OSI model Data Link Layer's primary function:
   1. a) Packet routing
   2. b) Error detection & correction
   3. c) end-to-end communication
   4. d) Data encryption
4. Hyper-threading:
   1. a) Creates multiple physical cores
   2. b) Allows a single physical core to execute multiple threads simultaneously
   3. c) Reduces cache size
   4. d) Only applied to GPU
5. The minimum number of NAND gates required to implement an OR gate is:
   1. a) 1
   2. b) 2
   3. c) 3
   4. d) 4
6. A half-adder circuit has:
   1. a) 1 input, 2 outputs
   2. b) 2 inputs, 2 outputs
   3. c) 2 inputs, 1 output
   4. d) 3 inputs, 2 outputs
7. Reduces redundancy and improves integrity:
   1. a) Indexing
   2. b) Normalization
   3. c) Denormalization
   4. d) Partitioning
8. Which command can we use to save all transactions?
   1. a) savepoint
   2. b) commit
   3. c) save
   4. d) rollback
9. The bisection method is used to:
   1. a) Find the eigenvalue of a matrix
   2. b) Solve a system of linear equation
   3. c) find roots of non-linear equations
   4. d) Perform numerical integration
10. In machine learning, supervised learning means:
    1. a) training with unlabeled data
    2. b) no training is required
    3. c) training with labeled data
    4. d) Only reinforcement signals are used
11. What does the 'continue' statement do inside a loop?
    1. a) exits the loop entirely
    2. b) terminates the program
    3. c) re-executes the loop twice
    4. d) skips the rest of the current iteration and moves to the next
12. Which register in a CPU points to the next instruction to be executed?
    1. a) Accumulator
    2. b) Flags
    3. c) SP
    4. d) PC
13. Intel 8085 microprocessor is a ________ bit microprocessor.
    1. a) 8
    2. b) 16
    3. c) 32
    4. d) 64
14. Which of the following is not a characteristic of problems suited for Dynamic programming (SP means subproblems)?
    1. a) Overlapping SP
    2. b) Optimal substructure
    3. c) Independent SP
    4. d) Repeated computation of SP
15. The chromatic index of a bipartite graph with at least one edge is:
    1. a) 1
    2. b) 2
    3. c) 3
    4. d) 4
16. In Huffman coding, the algorithm repeatedly picks two nodes and merges those. These two nodes are:
    1. a) with the highest frequency
    2. b) with the lowest frequency
    3. c) one highest and one lowest frequency
    4. d) picked arbitrarily
17. A primary key:
    1. a) Can have NULL
    2. b) Uniquely identifies each row
    3. c) Must be a foreign key
    4. d) Can have duplicates
18. The address block 192.168.16.0/20 contains ________ IP addresses.
    1. a) 1024
    2. b) 4096
    3. c) 2048
    4. d) 65536
19. A* search algorithm is:
    1. a) only complete but not optimal
    2. b) Only optimal but not complete
    3. c) complete and optimal if the heuristic is admissible
    4. d) Neither optimal nor complete
20. Which of the following protocols is used together with HTTP in HTTPS?
    1. a) SHA
    2. b) SSH
    3. c) TLS
    4. d) VPN
21. ________ is used in C to write a single character to a file.
    1. a) fputs()
    2. b) fprintf()
    3. c) putc()
    4. d) fwrite()
22. "Either all of its operations are executed or none." - this refers to:
    1. a) Consistency
    2. b) Isolation
    3. c) Atomicity
    4. d) Durability
23. ________ algorithm is used to find a shortest path in a positive weighted graph.
    1. a) Prim's
    2. b) Kruskal's
    3. c) Dijkstra's
    4. d) DFS
24. Pushdown automata (PDA) is equivalent in power to:
    1. a) regular expressions
    2. b) context-free grammars
    3. c) context-sensitive grammars
    4. d) Turing machines
25. ________ operates at the network layer and is used to connect different networks.
    1. a) Hub
    2. b) Switch
    3. c) Router
    4. d) Repeater
26. ________ method is a first order optimization method
    1. a) Newton
    2. b) Quasi-Newton
    3. c) Gradient descent
    4. d) Conjugate gradient
27. Which one below is an iterative method?
    1. a) Gauss elimination
    2. b) Gauss-Seidel
    3. c) Cramer's rule
    4. d) Matrix inversion
28. In C, to retain the values of variables between function calls, we should use:
    1. a) auto
    2. b) extern
    3. c) static
    4. d) register
29. Which phase in the compiler design performs data type checking?
    1. a) Lexical analysis
    2. b) Syntax analysis
    3. c) Semantic analysis
    4. d) Code generation
30. For an n-element min-Heap:
    1. a) the smallest element can be found anywhere in the heap
    2. b) It is a type of binary search tree.
    3. c) accessing an arbitrary element is an O(n) operation.
    4. d) the largest element is always at the root.
31. For BFS of a graph, we should use:
    1. a) queue
    2. b) Stack
    3. c) priority queue
    4. d) Binary search tree
32. Which optimization technique is not used for eliminating redundant code?
    1. a) Dead code elimination
    2. b) Partial redundancy elimination
    3. c) Common subexpression elimination
    4. d) Constant folding
33. ________ layer of the TCP/IP model is responsible for port binding.
    1. a) Application
    2. b) Internet
    3. c) Transport
    4. d) Network
34. Which one below is an example of a NoSQL database?
    1. a) MySQL
    2. b) MongoDB
    3. c) Oracle
    4. d) PostgreSQL
35. A complete graph of n vertices has ________ edges.
    1. a) n
    2. b) n(n+1)/2
    3. c) n(n-1)/2
    4. d) n²
36. What is the hexadecimal value of (1111011011)₂?
    1. a) 3BD
    2. b) 3DB
    3. c) 3CB
    4. d) 3DA
37. Which one is a compile-time polymorphism?
    1. a) Virtual function
    2. b) Operator overloading
    3. c) Function overriding
    4. d) Dynamic binding
38. Data ________ is the ability to modify a schema definition in a level without affecting the next higher level.
    1. a) binding
    2. b) abstraction
    3. c) mapping
    4. d) independence
39. ________ is a non-preemptive algorithm.
    1. a) FCFS
    2. b) Round Robin
    3. c) Shortest Remaining Time
    4. d) None of the above
40. The main difference between a latch (L) and a flip-flop (FF) is:
    1. a) FF is level-triggered, L is edge-triggered
    2. b) FF is edge-triggered, L is level-triggered
    3. c) FF cannot store data but L can
    4. d) L can store more data than a FF
41. What is the role of an Index in a database?
    1. a) To store large binary objects
    2. b) To store data integrity constraints
    3. c) To group the related table together
    4. d) To boost the speed of data retrieval operations
42. Which of the following will delete all records from the table with the table structure?
    1. a) ALTER
    2. b) DELETE
    3. c) DROP
    4. d) TRUNCATE
43. In OOP, ________ is used to restrict access to certain details of an object.
    1. a) Inheritance
    2. b) Polymorphism
    3. c) Abstraction
    4. d) Encapsulation
44. To solve a problem using recursion we should use a:
    1. a) Linked list
    2. b) stack
    3. c) queue
    4. d) array
45. In Agile, Software is delivered:
    1. a) at the end of the project
    2. b) in small incremental iterations
    3. c) after complete documentation
    4. d) only when all features have been implemented
46. UDP is a ________ protocol.
    1. a) Connection-less
    2. b) Connection-oriented
    3. c) application layer
    4. d) Network access layer
47. The number of binary strings of length 5 is:
    1. a) 10
    2. b) 25
    3. c) 32
    4. d) 64
48. Which one is correct to declare & initialize an array in C?
    1. a) int arr(5) = (1,2,3,4,5);
    2. b) int arr[5] = {1,2,3,4,5};
    3. c) int arr() = 1,2,3,4,5;
    4. d) Array arr(5) = {1,2,3,4,5};
49. A relation R on a set B is an equivalence relation if it is:
    1. a) Reflexive and symmetric
    2. b) Reflexive and transitive
    3. c) symmetric and transitive
    4. d) Reflexive, symmetric and transitive
50. ________ refers to information about data
    1. a) Hyper data
    2. b) Tera data
    3. c) Meta data
    4. d) Big data
51. Which one is not an addressing mode?
    1. a) Immediate
    2. b) Direct
    3. c) Indirect
    4. d) Sequential
52. Using ________ order we can delete tree nodes in such a way that a child node is deleted before its parent
    1. a) Pre
    2. b) Post
    3. c) In
    4. d) Level
53. The Principle of Locality in memory systems helps to:
    1. a) reduce CPU clock cycles
    2. b) Improve cache performance
    3. c) increase instruction length
    4. d) Reduce I/O latency
54. Which of the following is a combinational circuit?
    1. a) Counter
    2. b) Flip-flop
    3. c) Multiplexer
    4. d) Register
55. Which one is true for a DFA?
    1. a) DFA can have ε-transitions
    2. b) DFA accepts all context-free languages
    3. c) DFA accepts regular languages
    4. d) DFA can have multiple transitions for the same input from a state
56. Greedy methods guarantee an optimal solution when:
    1. a) Overlapping subproblems exist
    2. b) problems have optimal substructure and greedy choice property
    3. c) divide and conquer can be applied
    4. d) Subproblems are independent
57. Adaptive maintenance is required when:
    1. a) errors are found in software
    2. b) user requirements are stable
    3. c) documentation is missing
    4. d) The environment such as OS, hardware changes
58. What output will be generated by the compiler after lexical and syntax analyses, respectively?
    1. a) Tokens and a parse tree
    2. b) A parse tree and tokens
    3. c) A syntax tree and intermediate code
    4. d) Tokens and error messages
59. Contrapositive of "If it rains, the home team wins":
    1. a) If the home team wins, then it rains
    2. b) If the home team does not win, it does not rain
    3. c) If it does not rain then the home team does not win
    4. d) The home team wins whenever rains
60. Which one is a supervised learning algorithm?
    1. a) K-means
    2. b) Decision tree
    3. c) Apriori
    4. d) DBSCAN
61. Which of the following is a numerical method for eigenvalue problems?
    1. a) Gauss elimination
    2. b) Power method
    3. c) Newton interpolation
    4. d) Trapezoidal rule
62. Direct Memory Access allows:
    1. a) CPU to execute instructions while I/O transfers data directly to memory
    2. b) Only CPU controlled data transfer
    3. c) memory to execute instructions independently
    4. d) Reducing cache hits
63. ________ replaces the page that has not been used for the longest time:
    1. a) MRU
    2. b) LRU
    3. c) FIFO
    4. d) LIFO
64. Cache hit rate = 80%; cache access time = 5 ns; memory access time = 50 ns. Then, effective access time (in ns):
    1. a) 15 ns
    2. b) 45 ns
    3. c) 50
    4. d) 55
65. Which one is false with respect to a VLAN?
    1. a) Provides a logical separation on Layer 2
    2. b) Improves security
    3. c) VLAN tag can distinguish traffic
    4. d) Increases network management complexity
66. Which data structure allows insertion at one end and deletion at the other end?
    1. a) Stack
    2. b) Tree
    3. c) Queue
    4. d) Graph
67. What is the output of the following C code? #include<stdio.h> int main(){ int arr[5] = {1,2,3,4,5}; int *p = (arr+2); printf("%d", p[-1])…
    1. a) 2
    2. b) 3
    3. c) undefined behaviour
    4. d) Compilation error
68. In virtual memory, TLB is used to:
    1. a) store instructions
    2. b) control data transfers
    3. c) handle cache misses
    4. d) translate virtual address to physical address quickly
69. ____ sort uses a divide and conquer approach.
    1. a) Insertion
    2. b) Quick
    3. c) Bubble
    4. d) Selection
70. ________ is used to store web addresses for future use.
    1. a) Routing
    2. b) DNS resolution
    3. c) Caching
    4. d) ARP resolution
71. Consider 3 processes (P1, P2, P3) and 2 resources (R1, R2). If P1 holds R1 & requests R2, P2 holds R2 & requests R1, what is the minimum…
    1. a) 0 unit
    2. b) 1 unit of R1 or 1 unit of R2
    3. c) 2 units: 1 of R1 & 1 of R2
    4. d) Not enough information
72. The space complexity of a recursive algorithm is mainly due to:
    1. a) Input size
    2. b) Output size
    3. c) Variables inside loops
    4. d) Function call stack
73. ____ combines multiple signals over a single medium by assigning different time slots.
    1. a) FDM
    2. b) TDM
    3. c) WDM
    4. d) SDM
74. During a phone conversation, which mode of communication takes place?
    1. a) Simplex
    2. b) Full-duplex
    3. c) Half-duplex
    4. d) Multiplex
75. Garbage collection is required in SSD, because:
    1. a) SSD cells must be erased before being written
    2. b) SSDs cannot store large files
    3. c) SSDs do not support random access
    4. d) it reduces read latency
76. ________ uses disk space as an extension of RAM.
    1. a) Caching
    2. b) Virtual memory
    3. c) Spooling
    4. d) Buffer
77. Newton's backward interpolation formula is the most effective when:
    1. a) Interpolation point is near the beginning
    2. b) Interpolation point is near the end
    3. c) Data points are not equally spaced
    4. d) Function is non-polynomial
78. ____ testing is performed without knowledge of the internal implementation.
    1. a) White box
    2. b) Black box
    3. c) Unit
    4. d) Integration
79. Which criterion is not mandatory for a solution of critical section problem?
    1. a) Mutual exclusion
    2. b) Bounded waiting
    3. c) Circular Waiting
    4. d) Progress
80. Interrupt-driven I/O is preferred over polling because it :
    1. a) reduces CPU idle time
    2. b) is slower
    3. c) uses more memory
    4. d) requires fewer devices
81. For a connected acyclic graph with v vertices and e edges we have:
    1. a) v=e
    2. b) v=e+1
    3. c) v=e+2
    4. d) v+1=e
82. Thrashing in memory management occurs when:
    1. a) Page size is too small
    2. b) CPU utilization is very high
    3. c) The system spends more time swapping pages than executing processes
    4. d) Page table is too large
83. A 16-bit address bus can address a maximum of ________ KB memory.
    1. a) 16
    2. b) 32
    3. c) 64
    4. d) 128
84. In Agile, backlog refers to the list of:
    1. a) completed tasks
    2. b) pending bugs
    3. c) features and tasks to be developed
    4. d) rejected requirements
85. The register SP in a microprocessor:
    1. a) points to the first instruction
    2. b) points to the top of the stack
    3. c) holds the base address of the memory
    4. d) holds the I/O port address
86. A priority queue is best-implemented using a:
    1. a) Stack
    2. b) Linked list
    3. c) array
    4. d) heap
87. Which loop is an exit-controlled loop?
    1. a) for loop
    2. b) while loop
    3. c) do while loop
    4. d) None of the above
88. Which one is not an ACID property?
    1. a) Authenticity
    2. b) Consistency
    3. c) Isolation
    4. d) Durability
89. Which protocol is used to send an email over the Internet?
    1. a) FTP
    2. b) SMTP
    3. c) HTTP
    4. d) SNMP
90. Intel 8086 (16-bit) microprocessor has a ________ bit address bus.
    1. a) 8
    2. b) 16
    3. c) 20
    4. d) 32
91. Which of the following is the simplified version of Boolean function F = Ȳ (X + X̄Y)?
    1. a) X̄.Y
    2. b) X.Ȳ
    3. c) X.Y
    4. d) X̄.Ȳ
92. Which of the following is a guided transmission medium?
    1. a) Radiowave
    2. b) Microwave
    3. c) Coaxial Cable
    4. d) Infrared
93. Assuming P1, P2, P3 have burst time (in ms) 6, 8, 3, respectively, which statement is true about SJF?
    1. a) Waiting time of P1 is 3 ms
    2. b) Turn-around time of P3 is 9 ms
    3. c) Waiting time for P2 is 6 ms
    4. d) Turn-around time of P1 is 8 ms
94. OS system calls perform the following basic operations on files:
    1. a) Read, Write, Delete
    2. b) Write, Print, Reposition
    3. c) Delete, Truncate, Sort data
    4. d) Modify, update, sort data
95. A page fault occurs when:
    1. a) deadlock happens
    2. b) segmentation starts
    3. c) page is found in memory
    4. d) page is not found in memory
96. Alpha-Beta pruning can:
    1. a) change the final minimax result
    2. b) Only reduces the number of nodes evaluated
    3. c) increase the depth of the tree
    4. d) Increase the branching factor

Written (27)

1. (a) Mention two basic differences between 'call by value' and 'call by Reference'. Write a program in c/c++ Programming language to swap…
2. (a) Convert the numbers (16A.6)₁₆ and (72.3)₈ in binary format and show their summation in Hexadecimal format. (b) Explain properties of…
3. (a) Consider you are given two sets- A= {2, 3, 5, 9}, B = {5, 7, 9, 11}; What will be the output for the following set operations? (i) A∪B…
4. (a) Analyze the time and space complexity of the following code snippet: for i in N: for j in M: print (i,j) (b) What are the required…
5. (a) Differentiate between process and thread. (b) Draw and explain the process state transition diagram of an operating system. (c) What…
6. (a) What is a DBMS? Explain the advantages and disadvantages of DBMS. (b) Why do we use a trigger? Write a trigger that inserts the…
7. (a) Describe the TCP/IP model. (b) Given IP address: 172.16.128.120/25, what is the subnet mask, network address, broadcast address and…
8. (a) Write down the Maxwell's equations in integral form and explain their physical interpretations in electromagnetics. (b) Define phase…
9. (a) Explain Thevenin's theorem. Describe the steps required to find the Thevenin equivalent voltage and resistance of a given linear…
10. (a) Define Boolean algebra. State its fundamental laws and illustrate how these laws are applied to simplify logic expressions. (b) What…
11. (a) What are the differences between Harvard and Von Neumann architecture? Explain using a suitable diagram. (b) How does DMA increase…
12. (a) Explain the concept of Entropy in information theory. How does it quantify the uncertainty of a random message source? (b) Compare…
13. (a) Define constructor, destructor, and copy constructor in object-oriented programming context. (b) Write a program in C++ to check…
14. (a) Define a graph and explain the concepts of degree, path, cycle, and connectedness in an undirected graph: Differentiate between…
15. (a) Explain the differences between stack and queue data structures in terms of their operations, memory organization and real-life…
16. (a) State and explain the "Law conservation of bugs". (b) What is the basic function of paging in OS? Why the page sizes are always power…
17. (a) Explain the concept of congestion control in computer networks. Discuss briefly how TCP manages congestion during data transmission…
18. (a) In the case of C programming, how does pointer arithmetic behave? Illustrate with an example. (b) How do recursion and iteration…
19. (a) What are the purposes of using the protocols ARP and DVR? Explain with examples. (b) What is Ethernet? Briefly describe technical…
20. (a) Discuss how floating point representation contributes to rounding errors. (b) Through Newton-Raphson method, determine a root of the…
21. (a) For the frequencies given below, construct a Huffman Tree and compute Average Code Length. {A:5, B:9, C:12, D:13, E:16, F:45} (b) With…
22. (a) Discuss the roles of different segment registers and offset registers of 8086 microprocessor with examples. (b) How are the byte and…
23. (a) What are the steps of operation of a compiler? Describe the tasks of each of the steps. (b) Compare the characteristics and…
24. (a) Consider the following Bank database, where the Primary keys are shown in bold. branch (branch_name, branch_city, assets) customer…
25. (a) What is Regression testing and why is it important? (b) What is a Sandbox? Why is it used in Software Development? (c) What is meant…
26. (a) Differentiate between Supervised learning & Unsupervised learning with examples. (b) How do neural networks distinguish useful…
27. (a) Compare between IPv4 and IPv6 headers. (b) Elaborate the processes of CSMA/CD and CSMA/CA. (c) Explain how "Diffie Hellman Key…

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