JNU 2018-1 PhD CS

Question 1
Recursively enumerable languages are not closed under
A
concatenation
B
complement
C
union
D
homomorphism
Question 1 Explanation: 
Recursively enumerable languages are closed under concatenation,union,homomorphism but not closed under complementation
Question 2
Let L be a language that can be recognized by a finite automaton. The language LR consisting of reverse of the elements of L is a
A
regular language
B
context-free language
C
context-sensitive language
D
recursive language
Question 2 Explanation: 
The language that can be recognized by a finite automata is called regular language.And regular language is closed under reversal
Question 3

Consider the following context-free grammar:

S → XY, X → aX | bX | a, Y → Ya | Yb | a

A string generated by this grammar has
A
at least one b
B
no consecutive a’s or b’s
C
at least two a’s
D
last symbol as a
E
None of the above
Question 3 Explanation: 
Let's check option wise,
Option a is false because string “aa” is generated by the given grammar which does not contain b’s.
Option b is false because string “aa” is generated by the given grammar which contains consecutive a’s.
Option d is false because string “aba” contains the last symbol as ‘a’ but not generated by the grammar.
Option c is also false because string “aba” contains two a’s but not generated by the grammar.
Question 4
The basic logic of pumping lemma can be considered as a good example of
A
recursion
B
iteration
C
pigeonhole principle
D
divide-and-conquer
Question 4 Explanation: 
The pigeonhole principle states that if you have fewer holes than objects then at least one holes has multiple objects in it.It states that put one object in each hole and then there must exist at least one hole which must have more than one object.
In the theory of formal languages in computability theory, a pumping lemma or pumping argument states that, for a particular language to be a member of a language class, any sufficiently long string in the language contains a section, or sections, that can be removed, or repeated any number of times, with the resulting string remaining in that language. The proofs of these lemmas typically require counting arguments such as the pigeonhole principle. Hence, the logic of pumping lemma is a good example of the pigeonhole principle.
Question 5
Which of the following scheduling algorithms is non-preemptive?
A
Round-robin
B
First in, first out
C
Multilevel queue scheduling
D
Multilevel queue scheduling with feedback
Question 5 Explanation: 
First-in-first-out scheduling algorithms are non preemptive scheduling algorithms because in this the process is served according to first come first served manner.
Question 6
The part of machine level instruction, which tells central processor what has to be done, is
A
address
B
locator
C
operation code
D
flip-flop
Question 6 Explanation: 
An opcode (abbreviated from operation code), also known as instruction machine code, is the portion of a machine language instruction that specifies the operation to be performed. Beside the opcode itself, most instructions also specify the data they will process, in the form of operands.
Question 7
Which module gives control of the CPU to the process selected by the short-term scheduler?
A
Dispatcher
B
Interrupt
C
Scheduler
D
None of the above
Question 7 Explanation: 
The process is selected by the scheduler and then it is the dispatcher who gives the control of the CPU to the process selected by the scheduler
Question 8
Which of the following is the locality of reference used in OS?
A
Memory is the locality in the system
B
Cache memory is local memory
C
Main memory is local memory
D
Control moves from one locality to another during the execution
Question 8 Explanation: 
Cache operation is based on the principle of locality of reference. There are two ways with which data or instruction is fetched from main memory and get stored in cache memory. These two ways are the following:
->Spatial locality
->Temporal locality
Question 9
The database does not have the component
A
user data
B
metadata
C
reports
D
indexes
Question 9 Explanation: 
Component of database includes indexes, data dictionary, metadata, description. But reports are not components. It is generated by user according to their need.
Question 10
Data duplication is affected by normalization in the way it
A
eliminates
B
reduces
C
increases
D
does not affect at all
Question 10 Explanation: 
Database normalization is the process of structuring the relational database in accordance with the series of so called normal forms in order to reduce data redundancy and improve data integrity.
Question 11
There are no multivalued attributes and also no partial dependencies in a relation. The relation is in
A
first normal form
B
second normal form
C
third normal form
D
fourth normal form
Question 11 Explanation: 
A relation is in 2NF or second normal form if there is no partial dependencies in a relation.
Question 12
Relational algebra is related to
A
metalanguage
B
data definition language
C
procedural query language
D
non-procedural query language
Question 12 Explanation: 
Relational algebra is procedural query language.
Question 13
Which of the following operations can be applied on arrays?
A
Updation
B
Addition
C
Deletion
D
All of the above
Question 13 Explanation: 
An array is collection of items stored at contiguous memory locations. The idea is to store multiple items of same type together. This makes it easier to calculate the position of each element by simply adding an offset to a base value, i.e., the memory location of the first element of the array
All of the above given operations can be applied on arrays.
Question 14
The binary search of n data elements needs at most the comparisons
A
log2(n) - 1
B
log2(n)+ 1
C
log2(n) - 2
D
log2(n) - 4
Question 15
Which is not true for a B-tree of order m?
A
Leaf nodes must be at the same level
B
All the key values within a node must be in ascending order
C
All non-leaf nodes must have at least m/2 children
D
A non-leaf node with (n-1) keys must have n numbers of children
Question 15 Explanation: 
Option c is false because if non leaf node is root node then it can have atleast two children
Question 16
Which is not true about the graphs, assuming number of nodes/vertices as n?
A
They can be represented by using adjacency list
B
They can be represented by using adjacency matrix
C
They can be represented by using incidence matrix
D
Addition of a node has complexity O(n)
Question 16 Explanation: 
Question 17
A program written in C is converted into machine language using
A
interpreter
B
compiler
C
editor
D
loader
Question 17 Explanation: 
A compiler takes the program code (source code) and converts the source code to a machine language module (called an object file).
Question 18
Consider the following statements inC: int arr[10];
A
arr and &arr[0] point to the address of first element
B
arr[0] is equivalent to *arr
C
Both (a) and (b) are correct
D
Either (a) or (b) is correct
Question 18 Explanation: 
Option a is correct. Option b is correct because arr[i] is equivalent to *(arr+i).
Question 19

#include

long int mNumber(int n);

int main( )

{

scanf(“%d”, &n)

printf(“%d”, mNum(n));

return 0;

}

long int mNum(int n);

{

return n * mNum(n-1);

}



Consider the above program, if a user enters input 5, the output will be
A
120
B
nNum(5)
C
4!
D
Cannot be computed
Question 19 Explanation: 
The output cannot be computed because there is no terminating condition in the function mNum(), and so the function will fall into infinite loop whatever value is given;
Question 20

Main ( )

{

printf(“\no borrow from”);

printf(“\bablu or”);

printf(“\rohit”);

}



The output is
A
no borrow from bablu or rohit
B
no bablu rohit borrow or from
C
Both are correct depending on the process
D
None of the above
Question 20 Explanation: 
The output is ohitrrow froablu or
Question 21
The software interrupts in 8085 are in numbers
A
5
B
8
C
12
D
16
Question 21 Explanation: 
There are 8 software interrupts in 8085 microprocessor.
Question 22
To avoid the race condition, the number of processes that may be simultaneously inside a critical section is
A
7
B
5
C
3
D
1
Question 22 Explanation: 
Race condition occurs if more than one processes is inside the critical section. So to avoid race condition only 1 process should be allowed inside the critical section.
Question 23
Stack pointer in 8085 is
A
a 16-bit register microprocessor used to indicate the beginning of stack memory
B
a register used to decode and execute 16-bit arithmetic expression
C
first memory location used to store a subroutine address
D
a register used to flag bits
Question 23 Explanation: 
For 8085: Stack pointer is a special purpose 16-bit register in the Microprocessor, which holds the address of the top of the stack.
Question 24
Which determines the address of I/O interface?
A
Register select
B
Chip select
C
Both of the above
D
None of the above
Question 25
The network layer does not have the functionality
A
routing
B
inter-networking
C
congestion control
D
error correction
Question 25 Explanation: 
Routing, inter-networking and congestion control are the functionality of network layer but error correction is not the functionality of network layer.
Question 26
An endpoint of an inter-process communication flow across a computer network is called
A
socket
B
pipe
C
port
D
named pipe
Question 26 Explanation: 
An endpoint of an inter-process communication flow across a computer network is called the socket.
Question 27
Transport layer protocol is associated to
A
application to application
B
process to process
C
node to node
D
end to end
Question 27 Explanation: 
Transport layer protocol is associated to end to end communication
Network layer protocol is associated to process to process or host to host communication.
Data link layer protocol is associated to node to node communication.
Question 28
A packet travels from one end system to another end system. The delay occurring in travelling the packet is
A
propagation delay
B
queuing delay
C
transmission delay
D
All of the above
Question 28 Explanation: 
When a packet has to travel from one end system to another, it first faces the queuing delay when there are multiple packets which are to be sent, then it faces the transmission delay to convert the packet into bits to be transmitted, and then it faces the propagation delay to propagate the bits through.
Question 29
A packet travels from one end system to another end system. The delay occurring in travelling the packet is
A
propagation delay
B
queuing delay
C
transmission delay
D
All of the above
Question 29 Explanation: 
When a packet has to travel from one end system to another, it first faces the queuing delay when there are multiple packets which are to be sent, then it faces the transmission delay to convert the packet into bits to be transmitted, and then it faces the propagation delay to propagate the bits through.
Question 30
A function f(x) is defined as f(x) = x - [x], where [∙] represents the greatest integer function (GIF). Then
A
f(x) will be integral part of x
B
f(x) will be fractional part of x
C
f(x) will always be zero
D
f(x) will always be non-zero
Question 30 Explanation: 
The value of x can be any real no. but [x] will be only integral part of x. Hence x - [x] will be always fractional part of x.
Question 31
Let f and g be functions from the set of integers to itself, defined by f(x) = (x + 1)2 and g(x) = x2 + 1. Then the function f∘g is
A
(x^2+2)^2
B
(x^2+1)^2
C
(x^2+1)^2 (x^2+1)
D
None of the above
Question 31 Explanation: 
Question 32
The variance of the binomial distribution with parameters n and p is given by
A
p
B
np
C
p(1 - p)
D
np(1 - p)
Question 32 Explanation: 
The mean of the binomial distribution is np and the variance of binomial distribution is np(1-p).
Question 33
The mean of the exponential distribution with parameter λ is given by
A
λ
B
1/λ
C
λ2
D
λ(1 - λ)
Question 33 Explanation: 
The mean of the exponential distribution is 1/λ .
Question 34
The ratio of the mean to the variance of the Poisson distribution with parameter λ is given by
A
λ
B
1/λ
C
1
D
1 - λ
Question 34 Explanation: 
The mean and variance of the poisson distribution is same and it is λ . So the ratio of mean to variance will be λ/λ = 1.
Question 35
Which of the following distributions has the property of being memoryless?
A
Normal
B
Bernoulli
C
Binomial
D
Exponential
Question 35 Explanation: 
The memoryless property (also called the forgetfulness property) means that a given probability distribution is independent of its history. Any time may be marked down as time zero.
If a probability distribution has the memoryless property the likelihood of something happening in the future has no relation to whether or not it has happened in the past. The history of the function is irrelevant to the future.
The exponential distribution has the property of being memoryless.
Question 36
In the beta distribution, the expected value of the random variable x is calculated as
A
E(x) = m /(m-n)
B
E(x) = m /(m+n)
C
E(x) = n /(m+n)
D
E(x) = n/(m*n)
Question 36 Explanation: 
In probability theory and statistics, the beta distribution is a family of continuous probability distributions defined on the interval [0, 1] parameterized by two positive shape parameters, denoted by α and β, that appear as exponents of the random variable and control the shape of the distribution.
The expected value (mean) (μ) of a Beta distribution random variable X with two parameters α and β is a function of only the ratio β/α of these parameters:
Question 37
Process in which the trials are statistically independent and each trial of event has only two outcomes is classified as
A
Bayes process
B
functional process
C
independent limited process
D
Bernoulli process
Question 37 Explanation: 
In the theory of probability and statistics, a Bernoulli trial (or binomial trial) is a random experiment with exactly two possible outcomes, "success" and "failure", in which the probability of success is the same every time the experiment is conducted.
Question 38
The expected value of the random variable x of gamma distribution is
A
E(x)=pq/μ
B
E(x)=μ/np
C
E(x)=n/μ
D
E(x)=α/μ
Question 39
If we toss a biased coin that has P(H) = 2P(T), then the probability of coming head is
A
0
B
1/2
C
1/3
D
2/3
Question 39 Explanation: 
Question 40
The covariance cov(X, Y) of two independent random variables X and Y is
A
0
B
1
C
-1
D
var(X) var(Y)
Question 40 Explanation: 
The covariance cov(X,Y) of two independent random variables X and Y is 0.
Question 41
A set of all possible outcomes of an experiment is called
A
combination
B
sample point
C
compound event
D
sample space
Question 41 Explanation: 
The set of all possible outcomes for an experiment is called a sample space.
Question 42
Classroom communication must be
A
teacher-centric
B
student-centric
C
general-centric
D
textbook-centric
Question 42 Explanation: 
Classroom communication must be student centric because teacher should come to the class for teaching to student. He does not take general or his personal topics. He has to find the need of students. Teacher should also check abilities, interests, and learning styles. On this basis, he has to communicate to his students.
Question 43
The type of communication that a teacher has in the class is termed as
A
interpersonal
B
mass communication
C
group communication
D
face-to-face communication
Question 43 Explanation: 
The term "group communication" refers to the messages that are exchanged by group members. These messages, whether verbal or nonverbal, are important to groups because it is through the exchange of messages that group members participate, maintain the group identity, determine goals, motivate participation, and do the many things that keep the group intact
Question 44
Interaction inside the class should generate
A
argument
B
information
C
ideas
D
controversy
Question 44 Explanation: 
When you as teacher gives the opportunity to your students to talk and interact, you should not allow to give argument. . So, he should motivate students for generating new ideas.
Question 45
The best method of teaching is to
A
initiate discussion and participate
B
import information
C
ask students to read books
D
suggest good reference material
Question 46
Teacher’s most precious asset is
A
his/her job
B
student’s faith
C
prejudice
D
books
Question 47
The most important thing in the behaviour of a teacher is
A
dominance
B
discipline
C
sympathy
D
patience
Question 48
Which of the following is not research?
A
Exploratory research study
B
Descriptive research study
C
Diagnostic research study
D
Populistic research study
Question 49
Successful teacher is one who can
A
teach subject text properly
B
describe the subject
C
encourage the students
D
help in evaluation
Question 50
The number of significant digits in the number 4.3700×10Ms-2 is
A
3
B
4
C
5
D
6
Question 50 Explanation: 
4.3700×(10^-2) = 0.043700 =0.0437 = .0437 . Hence the no. of significant digits in the given no. is 4.
Question 51
The research that aims at finding the solutions for an intermediate problem faced by a society, industry or business organization can be closely related to
A
applied research
B
fundamental research
C
conceptual research
D
primary research
Question 51 Explanation: 
Applied research aims at finding a solution for an immediate problem facing a society, or an industrial/business organisation
Question 52
Round-off error in the number 6.436 rounded off to 6.44 is
A
0.0062%
B
0.062%
C
0.62%
D
6.2%
Question 52 Explanation: 
Question 53
ANOVA stands for
A
Analysis of Vector
B
Analysis of Validation
C
Analysis of Variance
D
Analysis of Variability
Question 53 Explanation: 
Analysis of variance, a statistical method in which the variation in a set of observations is divided into distinct components.
Question 54
A good research should be
A
logical
B
replicable
C
systematic
D
All of the above
Question 54 Explanation: 
To qualify as good research, the process must have certain characteristics and properties: it must, as fair as possible, be controlled, rigorous, systematic, valid and verifiable, empirical and critical.
Question 55
A good research investigating the reasons for human behaviour could be closely termed as
A
quantitative research
B
qualitative research
C
fundamental research
D
simulation research
Question 55 Explanation: 
The aim of a qualitative research project may vary with the disciplinary background, such as a psychologist seeking in-depth understanding of human behavior and the reasons that govern such behavior for example. Qualitative methods are best for researching many of the why and how questions of human experience, in making a decision for example (not just what, where, when, or "who"); and have a strong basis in the field of sociology to understand government and social programs
Question 56
Through the principle of replication, the accuracy of experiments
A
is increased
B
is decreased
C
is not affected
D
may decrease or increase
Question 56 Explanation: 
According to the Principle of Replication, the experiment should be repeated more than once. Thus, each treatment is applied in many experimental units instead of one. By doing so the statistical accuracy of the experiments is increased. ... The entire experiment can even be repeated several times for better results.
Question 57
Given E(x) = 5 and E(Y) = -3, then E(3X + 2Y) is
A
3
B
5
C
9
D
-2
Question 57 Explanation: 
E(3X + 2Y) = 3E(X) + 2E(Y) = 3*5 + 2*-3 = 15 - 6 = 9
Question 58
Which of the following inequalities is useful for interpreting variances?
A
Chebyshev
B
Statutory
C
Testory
D
All of the mentioned
Question 58 Explanation: 
Chebyshev's inequality is useful for interpreting variances.
Question 59
The weight of persons in a city is a random variable of type
A
discrete random variable
B
continuous random variable
C
mixed-type random variable
D
None of the above
Question 59 Explanation: 
Continuous random variables have numeric values that can be any number in an interval. For example, the (exact) weight of a person is a continuous random variable. Foot length is also a continuous random variable. Continuous random variables are often measurements, such as weight or length.
Question 60
Which of the following is not a type of research design?
A
Confirmatory research design
B
Descriptive and diagnostic research design
C
Exploratory research design
D
Hypothesis-testing research design
Question 61
A
0
B
C
1
D
f(x) + 1
Question 61 Explanation: 
There are 61 questions to complete.