Explore topic-wise MCQs in Computer Science.

Consider a 128×10 3 bits/second satellite communication link with one way propagation delay of 150 milliseconds. Selective retransmission (repeat) protocol is used on this link to send data with a frame size of 1 kilobyte. Neglect the transmission time of acknowledgement. The minimum number of bits required for the sequence number field to achieve 100% utilization is ___________

For the IEEE 802.11 MAC protocol for wireless communication, which of the following statements is/are TRUE?

I. At least three non-overlapping channels are
   available for transmissions.
II. The RTS-CTS mechanism is used for collision detection.
III. Unicast frames are ACKed.

A network has a data transmission bandwidth of 20 × 10 6 bits per second. It uses CSMA/CD in the MAC layer. The maximum signal propagation time from one node to another node is 40 microseconds. The minimum size of a frame in the network is _________ bytes.   Note : This question was asked as Numerical Answer Type.

where ri(Z) denotes a read operation by transaction Ti on a variable Z, wi(Z) denotes a write operation by Ti on a variable Z and ai denotes an abort by transaction Ti . Which one of the following statements about the above schedule is TRUE?

The smallest cache size required to ensure an average read latency of less than 6 ms is _______ MB

Consider a non-negative counting semaphore S. The operation P(S) decrements S, and V(S) increments S. During an execution, 20 P(S) operations and 12 V(S) operations are issued in some order. The largest initial value of S for which at least one P(S) operation will remain blocked is ________.

Consider the following two-process synchronization solution.

Process 0                             Process 1                          

Entry: loop while (turn == 1);        Entry: loop while (turn == 0);
       (critical section)                    (critical section)
       Exit: turn = 1;                       Exit turn = 0; 

The shared variable turn is initialized to zero. Which one of the following is TRUE?

A student wrote two context-free grammars G1 and G2 for generating a single C-like array declaration. The dimension of the array is at least one. For example,

int a[10][3]; 

The grammars use D as the start symbol, and use six terminal symbols int ; id [ ] num.

Grammar G1
D → int L;
L → id [E
E → num]
E → num] [E

Grammar G2
D → int L;
L → id E
E → E[num]
E → [num] 

Which of the grammars correctly generate the declaration mentioned above?

Consider the following languages.

L1 = { <M>  | M takes at least 2016 steps on some input},
L2 = { <M>  | M takes at least 2016 steps on all inputs} and
L3 = { <M>  | M accepts ε},

where for each Turing machine M,   <M> denotes a specific encoding of M. Which one of the following is TRUE?

Consider the following languages: L1 = {anbmcn : m, n >= 1} L2 = {anbnc2n : n >= 1} Which one of the following is TRUE?

Consider the following two statements:

I. If all states of an NFA are accepting 
   states then the language accepted by 
   the NFA is Σ∗ .
II. There exists a regular language A such 
    that for all languages B, A ∩ B is regular. 

Which one of the following is CORRECT?

In an adjacency list representation of an undirected simple graph G = (V, E), each edge (u, v) has two adjacency list entries: [v] in the adjacency list of u, and [u] in the adjacency list of v. These are called twins of each other. A twin pointer is a pointer from an adjacency list entry to its twin. If |E| = m and |V | = n, and the memory size is not a constraint, what is the time complexity of the most efficient algorithm to set the twin pointer in each entry in each adjacency list?

The number of ways in which the numbers 1, 2, 3, 4, 5, 6, 7 can be inserted in an empty binary search tree, such that the resulting tree has height 6, is _____________ Note: The height of a tree with a single node is 0. [This question was originally a Fill-in-the-Blanks question]

Let A1, A2, A3, and A4 be four matrices of dimensions 10 x 5, 5 x 20, 20 x 10, and 10 x 5, respectively. The minimum number of scalar multiplications required to find the product A1A2A3A4 using the basic matrix multiplication method is

Consider the following New-order strategy for traversing a binary tree: Visit the root; Visit the right subtree using New-order Visit the left subtree using New-order The New-order traversal of the expression tree corresponding to the reverse polish expression 3 4 * 5 - 2 ˆ 6 7 * 1 + - is given by:

A complete binary min-heap is made by including each integer in [1, 1023] exactly once. The depth of a node in the heap is the length of the path from the root of the heap to that node. Thus, the root is at depth 0. The maximum depth at which integer 9 can appear is _____________ [This question was originally asked as Fill-in-the-Blanks question]

Consider a 3 GHz (gigahertz) processor with a three-stage pipeline and stage latencies v1, v2, and v3 such that v1 = 3v2/4 = 2v3. If the longest pipeline stage is split into two pipeline stages of equal latency, the new frequency is _________ GHz, ignoring delays in the pipeline registers

The width of the physical address on a machine is 40 bits. The width of the tag field in a 512 KB 8-way set associative cache is ____________ bits

Consider a processor with 64 registers and an instruction set of size twelve. Each instruction has five distinct fields, namely, opcode, two source register identifiers, one destination register identifier, and a twelve-bit immediate value. Each instruction must be stored in memory in a byte-aligned fashion. If a program has 100 instructions, the amount of memory (in bytes) consumed by the program text is ____________ [Note that this was originally a Fill-in-the-Blanks question]

Suppose the functions F and G can be computed in 5 and 3 nanoseconds by functional units UFand UG, respectively. Given two instances of UF and two instances of UG, it is required to implement the computation F(G(Xi)) for 1 <= i <= 10. ignoring all other delays, the minimum time required to complete this computation is ________________ nanoseconds [Note that this is originally a Fill-in-the-Blanks Question]

The value of the expression 1399(mod 17), in the range 0 to 16, is :   Note : This question was asked as Numerical Answer Type.

Consider a set U of 23 different compounds in a Chemistry lab. There is a subset S of U of 9 compounds, each of which reacts with exactly 3 compounds of U. Consider the following statements:

I.  Each compound in U  S reacts with an odd number of compounds.
II.  At least one compound in U  S reacts with an odd number of compounds.
III.  Each compound in U  S reacts with an even number of compounds. 

Which one of the above statements is ALWAYS TRUE?

A binary relation R on N x N is defined as follows:

(a, b) R (c, d) if a <= c or b <= d.

Consider the following propositions:

P: R is reflexive
Q: R is transitive

Which one of the following statements is TRUE?

Identify the correct sequence in which the following packets are transmitted on the network by a host when a browser requests a webpage from a remote server, assuming that the host has just been restarted.

In an Ethernet local area network, which one of the following statements is TRUE ?

Anarkali digitally signs a message and sends it to Salim. Verification of the signature by Salim requires

Suppose a database schedule S involves transactions T1, ....Tn. Construct the precedence graph of S with vertices representing the transactions and edges representing the conflicts. If S is serializable, which one of the following orderings of the vertices of the precedence graph is guaranteed to yield a serial schedule?

B+ Trees are considered BALANCED because

In which one of the following page replacement algorithms it is possible for the page fault rate to increase even when the number of allocated frames increases?

Consider the following types of languages:

L1 Regular,
L2: Context-free,
L3: Recursive,
L4: Recursively enumerable. 

Which of the following is/are TRUE?

I.   L3' U L4 is recursively enumerable
II.  L2  U L3 is recursive
III. L1* U L2 is context-free
IV.  L1 U L2' is context-free 

Language L1 is defined by the grammar: S1 -> aS1b | ε
Language L2 is defined by the grammar: S2 -> abS2 | ε

Consider the following statements:

P: L1 is regular
Q: L2 is regular

Which one of the following is TRUE?

The number of states in the minimum sized DFA that accepts the language defined by the regular expression (0+1)*(0+1)(0+1)* is __________________ [Note that this question was originally asked as Fill-in-the-Blanks type]

N items are stored in a sorted doubly linked list. For a delete operation, a pointer is provided to the record to be deleted. For a decrease-key operation, a pointer is provided to the record on which the operation is to be performed. An algorithm performs the following operations on the list in this order: Θ(N) delete, O(log N) insert, O(log N) find, and Θ(N) decrease-key What is the time complexity of all these operations put together

The Floyd-Warshall algorithm for all-pair shortest paths computation is based on:

Assume that the algorithms considered here sort the input sequences in ascending order. If the input is already in ascending order, which of the following are TRUE ?

I.   Quicksort runs in Θ(n2) time
II.  Bubblesort runs in Θ(n2) time
III. Mergesort runs in  Θ(n) time
IV.  Insertion sort runs in  Θ(n) time 

Breadth First Search (BFS) is started on a binary tree beginning from the root vertex. There is a vertex t at a distance four from the root. If t is the n-th vertex in this BFS traversal, then the maximum possible value of n is ________ [This Question was originally a Fill-in-the-blanks Question]

A processor has 40 distinct instructions and 24 general purpose registers. A 32-bit instruction word has an opcode, two register operands and an immediate operand. The number of bits available for the immediate operand field is ____________ [This Question was originally a Fill-in-the-blanks Question]

Let X be the number of distinct 16-bit integers in 2’s complement representation. Let Y be the number of distinct 16-bit integers in sign magnitude representation. Then X −Y is _________ [This Question was originally a Fill-in-the-blanks Question]

Let, x1⊕x2⊕x3⊕x4 = 0 where x1, x2, x3, x4 are Boolean variables, and ⊕ is the XOR operator. Which one of the following must always be TRUE?

Consider an eight-bit ripple-carry adder for computing the sum of A and B, where A and B are integers represented in 2’s complement form. If the decimal value of A is one, the decimal value of B that leads to the longest latency for the sum to stabilize is _____________ [This Question was originally a Fill-in-the-blanks Question]

Suppose that the eigenvalues of matrix A are 1, 2, 4. The determinant of (A−1)T is _________ [This Question was originally a Fill-in-the-blanks Question]

Suppose that a shop has an equal number of LED bulbs of two different types. The probability of an LED bulb lasting more than 100 hours given that it is of Type 1 is 0.7, and given that it is of Type 2 is 0.4. The probability that an LED bulb chosen uniformly at random lasts more than 100 hours is :   Note : This question was asked as Numerical Answer Type.

Consider the systems, each consisting of m linear equations in n variables.

I. If m < n, then all such systems have a solution
II. If m > n, then none of these systems has a solution
III. If m = n, then there exists a system which has a solution

Which one of the following is CORRECT?

The minimum number of colours that is sufficient to vertex-colour any planar graph is _______________ [This Question was originally a Fill-in-the-blanks Question]

Let f (x) be a polynomial and g(x) = f (x) be its derivative. If the degree of (f(x) + f(−x)) is 10, then the degree of (g(x) − g(−x)) is _______________ [This Question was originally a Fill-in-the-blanks Question]

Consider the following expressions: (i) false (ii) Q (iii) true (iv) P ∨ Q (v) ¬Q ∨ P The number of expressions given above that are logically implied by P ∧ (P ⇒ Q) is ______________ [This Question was originally a Fill-in-the-blanks Question]

All hill-stations have a lake. Ooty has two lakes. Which of the statement(s) below is/are logically valid and can be inferred from the above sentences?

(i) Ooty is not a hill-station.
(ii) No hill-station can have more than one lake. 

Computers were invented for performing only high-end useful computations. However, it is no understatement that they have taken over our world today. The internet, for example, is ubiquitous. Many believe that the internet itself is an unintended consequence of the original invention. With the advent of mobile computing on our phones, a whole new dimension is now enabled. One is left wondering if all these developments are good or, more importantly, required. Which of the statement(s) below is/are logically valid and can be inferred from the above paragraph? (i) The author believes that computers are not good for us. (ii) Mobile computers and the internet are both intended inventions

Among 150 faculty members in an institute, 55 are connected with each other through Facebook ® and 85 are connected through WhatsApp ® . 30 faculty members do not have Facebook ® or WhatsApp ® accounts. The number of faculty members connected only through Facebook ® accounts is ______________.

Pick the odd one from the following options.