UGC NET Paper 2 Computer Science – December 2018 – Question Paper with Answer Key

In mathematical logic, which of the following are statements?

(i) There will be snow in January.

(ii) What is the time now ?

(iii) Today is Sunday.

(iv) You must study Discrete Mathematics.

Choose the correct answer from the code given below :

Match List I with List II and choose the correct answer from the code given below.

A box contains six red balls and four green balls. Four balls are selected at random from the box. What is the probability that two of the selected balls will be red and two will be green?

A survey has been conducted on methods of commuter travel. Each respondent was asked to check Bus, Train or Automobile as a major method of travelling to work. More than one answer was permitted. The results reported were as follows : Bus 30 people; Train 35 people; Automobile 100 people; Bus and Train 15 people; Bus and Automobile 15 people, Train and Automobile 20 people; and all the three methods 5 people. How many people completed the survey form?

Which of the following statements are true?

(i) Every logic network is equivalent to one using just NAND gates or just NOR gates.

(ii) Boolean expressions and logic networks correspond to labelled acyclic digraphs.

(iii) No two Boolean algebras with n atoms are isomorphic.

(iv) Non-zero elements of finite Boolean algebras are not uniquely expressible as joins of atoms.

The relations ≤ and < on a Boolean algebra are defined as: x ≤ y if and only if x ∨ y = y; x < y means x ≤ y but x ≠ y; x ≥ y means y ≤ x; and x > y means y < x. Considering these definitions, which of the following is not true in the Boolean algebra?

(i) If x ≤ y and y ≤ z, then x ≤ z

(ii) If x ≤ y and y ≤ x, then x = y

(iii) If x < y and y < z, then x ≤ y

(iv) If x < y and y < z, then x < y

The Boolean expression Ā·B + A·B̄ + A·B is equivalent to

In PERT/CPM, the merge event represents ___ of two or more events.

Use the dual simplex method to solve: Maximize z = −2x₁ − 3x₂ subject to x₁ + x₂ ≥ 2, 2x₁ + x₂ ≤ 10, x₁ + x₂ ≤ 8, x₁, x₂ ≥ 0.

In computers, subtraction is generally carried out by

Consider the following Boolean equations:

(i) wx + w(x + y) + x(x + y) = x + wy

(ii) (w x̄ (y + x z̄) + w̄ x̄) y = x̄ y What can you say about the above equations?

Consider the graph shown below :

Use Kruskal's algorithm to find the minimum spanning tree of the graph. The weight of this minimum spanning tree is

Consider the following statements :

(i) Auto increment addressing mode is useful in creating self-relocating code.

(ii) If auto increment addressing mode is included in an instruction set architecture, then an additional ALU is required for effective address calculation.

(iii) In auto increment addressing mode, the amount of increment depends on the size of the data item accessed. Which of the above statements is/are true?

A computer uses a memory unit with 256K words of 32 bits each. A binary instruction code is stored in one word of memory. The instruction has four parts: an indirect bit, an operation code, a register code part to specify one of 64 registers, and an address part. How many bits are there in the operation code, the register code part and the address part?

Consider the following x86 assembly language instructions: MOV AL, 153 NEG AL The contents of the destination register AL (in 8-bit binary), the status of the Carry Flag (CF) and the Sign Flag (SF) after executing these instructions are

The decimal floating point number -40.1 represented using IEEE-754 32-bit representation and written in hexadecimal form is

Find the boolean expression for the logic circuit shown below : (1-NAND gate, 2-NOR gate, 3-NOR gate)

Consider a disk pack with 32 surfaces, 64 tracks and 512 sectors per pack. 256 bytes of data are stored in a bit serial manner in a sector. The number of bits required to specify a particular sector in the disk is

Consider a system with 2 level cache. Access times of Level 1 cache, Level 2 cache and main 0.5 ns, 5 ns 100 ns memory are and respectively. The hit rates of Level 1 and Level 2 caches are 0.7 and 0.8 , respectively. What is the average access time of the system ignoring the search time within the cache?

If a graph G has no loops or parallel edges and has n ≥ 3 vertices, then G is Hamiltonian if

(i) deg(v) ≥ n/3 for each vertex v

(ii) deg(v) + deg(w) ≥ n whenever v and w are not connected by an edge

(iii) |E(G)| ≥ (1/3)(n − 1)(n − 2) + 2

The solution of recurrence relation : T(n) = 2T(sqrt(n)) + lg(n) is

The elements 42,25,30,40,22,35,26 are inserted one by one in the given order into a max-heap. The resultant max-heap is stored in an array implementation as

Consider two sequences X = ⟨0, 1, 2, 1, 3, 0, 1⟩ and Y = ⟨1, 3, 2, 0, 1, 0⟩. The length of the longest common subsequence of X and Y is

Consider the postfix expression with single-digit operands: 6 2 3 * / 4 2 * + 6 8 * −. The top two elements of the stack after the second * is evaluated are

A binary search tree is constructed by inserting the following numbers in order : 60,25,72,15,30,68,101,13,18,47,70,34 The number of nodes in the left subtree is

In a ternary tree, the number of internal nodes of degree 1,2 , and 3 is 4,3 , and 3 respectively. The number of leaf nodes in the ternary tree is

Match List I with List II and choose the correct answer from the code given below.

Where V and E are the number of vertices and edges in the graph respectively.

A K-colouring of an undirected graph G = (V, E) is a function c : V → {0, 1, …, K − 1} such that c(u) ≠ c(v) for every edge (u, v) ∈ E. For a 2-colourable graph G, which of the following is not correct?

Consider a singly linked list. What is the worst case time complexity of the best-known algorithm to delete the node a, pointer to this node is q, from the list?

The second smallest of n elements can be found with ____________ comparisons in the worst case.

Let r = a(a + b)*, s = aa*b and t = a*b be three regular expressions. Consider:

(i) L(s) ⊆ L(r) and L(s) ⊆ L(t)

(ii) L(r) ⊆ L(s) and L(s) ⊆ L(t)

Consider the language L = {a^(nk) | k > 0}, where n is a fixed non-negative integer. The minimum number of states of a finite automaton accepting L is

The number of substrings that can be formed from a string given by a d e f b g h n m p is

Consider the languages L₁ = {x | for some y with |y| = 2|x|, xy ∈ L} and L₂ = {x | for some y with |x| = |y|, xy ∈ L}, where L is a regular language. Which one is correct?

Consider L₁ = {a^(n+m) bⁿ aᵐ | n, m ≥ 0} and L₂ = {a^(n+m) b^(n+m) a^(n+m) | n, m ≥ 0}. Which one is correct?

Consider to be any regular language and L , L 1 2 be any two context-free languages. Which one of the following is correct?

Consider the following problems :

(i) Whether a finite state automaton halts on all inputs ?

(ii) Whether a given context free language is regular?

(iii) Whether a Turing machine computes the product of two numbers? Which one of the following is correct?

Which of the following problems is decidable for recursive languages L?

Consider the grammar G: S → A | B, A → a | c, B → b | c, with non-terminals {S, A, B} and terminals {a, b, c}. S₁: LR(1) can parse all strings generated by G. S₂: LL(1) can parse all strings generated by G.

The grammar S → (S) | SS | ε is not suitable for predictive parsing because the grammar is

If the frame buffer has 10-bits per pixel and 8- bits are allocated for each of the R, G, and B components, then what would be the size of the color lookup table (LUT) ?

Which homogeneous 2D matrix transforms the figure (a) on the left side to the figure (b) on the right ?

Consider the midpoint (Bresenham) algorithm for rasterizing lines: (1) Input (x₁, y₁) and (x₂, y₂) (2) y = y₁ (3) d = f(x₁ + 1, y₁ + 1/2) // f is the implicit form of the line (4) for x = x₁ to x₂ (5) do (6) plot(x, y) (7) if (d < 0) (8) then (9) y = y + 1 (10) d = d + (y₁ − y₂) + (x₂ − x₁) (11) else (12) d = d + (y₁ − y₂) (13) end (14) end Which statements are true? P: For a line with slope m > 1, the outer loop in line (4) should be over y. Q: Lines (10) and (12) update the decision variable d through an incremental evaluation of the line equation f. R: The algorithm fails if d is ever 0.

In 3D Graphics, which of the following statements about perspective and parallel projection is/are true? P : In a perspective projection, the farthest an object is from the centre of projection, the smaller it appears. Q : Parallel projection is equivalent to a perspective projection where the viewer is standing infinitely far away. R : Perspective projections do not preserve straight lines.

Choose the correct answer from the code given below :

In 3D Graphics, which of the following statements is/are true? P : Back-face culling is an example of an image- precision visible-surface determination procedure. Q : Z-buffer is a 16-bit, 32-bit, or 64-bit field associated with each pixel in a frame buffer that can be used to determine the visible surfaces at each pixel.

Consider the pseudo-code fragment, where m is a non-negative integer that has been initialized:

p = 0;
k = 0;
while (k < m)
    p = p + 2^k;
    k = k + 1;
end while

Which of the following is a loop invariant for the while statement? (A loop invariant is an assertion that is true each time the guard is evaluated.)

Consider the two C++ programs P1 and P2 shown below and two statements about them:

S1: P1 prints out 3

S2: P2 prints out 4:2 What can you say about S1 and S2?

Consider the following recursive Java function f that takes two long arguments and returns a

float value :
public static float f(long m, long n)
{
float result =(float )m/(float )n;
if (m<0||n<0)
return 0.0f ;
else
result +=f(m∗2,n∗3);
return result;
}

Which of the following integers best approximates the value of f(2,3)?

What does the following Java function perform? (Assume int occupies four bytes of storage) public static int f(

int a)
{ // Pre-conditions : a>0 and no
overflow/underflow occurs int b=0 ;
for (int i=0; i<32; i++)
{
b=b<<1 ;
b=b | (a & 1);
a=a≫>1;// This is a logical shift
}
return b;
}

Which of the following HTML5 codes will affect the horizontal as well as vertical alignment of the table content?

Consider the C/C++ function f() given below:

void f(char w[])
{
    int x = strlen(w); // length of the string
    char c;
    for (int i = 0; i < x; i++)
    {
        c = w[i];
        w[i] = w[x − i − 1];
        w[x − i − 1] = c;
    }
}

Which of the following is the purpose of f()?

Which of the following statements is/are false? P: The clean-room strategy for software engineering is based on the incremental software process model. Q: The clean-room strategy to software engineering is one of the ways to overcome "unconscious" copying of copyrighted code.

Consider the following method:

int f(int m, int n, boolean x, boolean y)
{
    int res = 0;
    if (m < 0) { res = n − m; }
    else if (x || y) {
        res = −1;
        if (n == m) { res = 1; }
    }
    else { res = n; }
    return res;
} /* end of f */

If P is the minimum number of tests for full statement coverage of f() and Q is the minimum number for full branch coverage, then (P, Q) =

Match the following Secret Key Algorithms (List I) with the Corresponding Key Lengths (List II) and choose the correct answer from the code given below.

The four byte IP Address consists of

Consider ISO-OSI network architecture reference model. Session layer of this model offers dialog control, token management and .________ as services.

The Third Generation mobile phones are digital and based on

Which of the following statement/s is/are true?

(i) Firewalls can screen traffic going into or out of an organization.

(ii) Virtual private networks can simulate an old leased network to provide certain desirable properties.

Which of the following statement/s is/are true?

(i) Windows XP supports both peer-peer and client-server networks.

(ii) Windows XP implements Transport protocols as drivers that can be loaded and unloaded from the system dynamically.

In Linux operating system environment _______ command is used to print a file.

To overcome difficulties in Readers-Writers problem, which of the following statement/s is/are true?

(i) Writers are given exclusive access to shared objects.

(ii) Readers are given exclusive access to shared objects.

(iii) Both Readers and Writers are given exclusive access to shared objects.

Suppose a system has 12 instances of some resource with n processes competing for that resource. Each process may require 4 instances of the resource. The maximum value of n for which the system never enters into deadlock is

Dirty bit is used to show the

Suppose for a process P, reference to pages in order are (1,2,4,5,2,1,2,4). Assume that main memory can accomodate 3 pages and the main memory has already pages 1 and 2 in the order 1 - first, 2 - second. At this moment, assume FIFO Page Replacement Algorithm is used then the number of page faults that occur to complete the execution of process P is

Consider the following processes with CPU burst times in milliseconds (table below). The processes are scheduled with Round-Robin scheduling with a time quantum of 4 ms. The waiting time for P₄ is ___ ms.

Suppose P, Q, and R are cooperating processes satisfying Mutual Exclusion conditions. Then, if Q the process is executing in its critical section then

A process residing in Main Memory and Ready and Waiting for execution is kept on?

______ system call creates new process in Unix.

An attribute A of datatype varchar(20) has the value 'xyz', and the attribute B of datatype char(20) has the value 'lmnop'. Then attribute A has ___ spaces and attribute B has ___ spaces.

Data warehouse contains _____ data that is never found in the operational environment.

_____command is used to remove a relation from an SQL database.

Which of the following statements is/are true?

(i) Facebook has the world's largest Hadoop cluster.

(ii) Hadoop 2.0 allows live stream processing of real-time data.

Data scrubbing is

Consider a relation schema R = (A, B, C, D, E, F) on which the following functional dependencies hold :

A → B B, C → D

E → C

D → A What are the candidate keys of R?

Consider two transactions on account A (initial balance 20,000): T1 transfers 5,000 to account B, then T2 applies 10% interest to A. The log is:

(i) T1 start

(ii) T1, A, old = 20,000, new = 15,000

(iii) T1, B, old = 12,000, new = 17,000

(iv) T1 commit

(v) T2 start

(vi) T2, A, old = 15,000, new = 16,500 (vii) T2 commit Suppose the database crashes just before log record (vii) is written. When the system restarts, which statement is true of the recovery process?

Consider the tables Students(Roll-No, Name) and Performance(Roll-No, Course, Marks) shown below; Students also contains the row (18CS103, Ramesh). Primary keys are underlined. Consider the query: SELECT S.Name, SUM(P.Marks) FROM Students S, Performance P WHERE S.Roll-No = P.Roll-No GROUP BY S.Name The number of rows returned is

A clustering index is defined on the fields which are of type

A host is connected to a department network which is part of a university network. The university network, in turn, is part of the Internet. The largest network, in which the Ethernet address of the host is unique, is

An ISP has the CIDR block 245.248.128.0/20. It wants to give half of it to organization A and a quarter to organization B, keeping the rest. Which is a valid allocation to A and B?

Consider the following two statements :

S1 : TCP handles both congestion and flow control

S2 : UDP handles congestion but not flow control Which of the following options is correct with respect to the above statements (S1) and S2)?

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.

Everyone in a group of N people wants to communicate secretly with the N − 1 others using a symmetric key system, with no pair's traffic decodable by the others. The number of keys required in the system as a whole is

An agent can improve its performance by

Which of the following is true for semi-dynamic environment?

Consider the following terminology and match

List I with List II and choose the correct answer from the code given below. b= branching factor d= depth of the shallowest solution m= Maximum depth of the search tree l = Depth limit

Match List I with List II and choose the correct answer from the code given below.

Consider the following statements :

S1: A heuristic is admissible if it never overestimates the cost to reach the goal.

S2: A heuristic is monotonous if it follows the triangle inequality property. Which one of the following is true referencing the above statements?

Consider the following statements related to AND-OR Search algorithm. S1 A solution is a subtree that has a goal node at every leaf. S2 OR nodes are analogous to the branching in a deterministic environment. S3 AND nodes are analogous to the branching in a non-deterministic environment. Which one of the following is true referencing the above statements ?

Consider the following minimax game tree search

What will be the value propagated at the root?

Consider a vocabulary with only four propositions A, B, C, and D. How many models are there for the following sentence? ¬A ∨ ¬B ∨ ¬C ∨ ¬D

Consider the sentence below. "There is a country that borders both India and Nepal." Which of the following represents the above sentence correctly?

A full joint distribution for the Toothache, Cavity, and Catch is given in the table below:

What is the probability of Cavity, given evidence of Toothache?