## JNU 2018-1 PhD CS

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Question 1 |

Recursively enumerable languages are not closed under

concatenation | |

complement | |

union | |

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

regular language | |

context-free language | |

context-sensitive language | |

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

at least one b | |

no consecutive a’s or b’s | |

at least two a’s | |

last symbol as a
| |

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.

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

recursion | |

iteration | |

pigeonhole principle | |

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.

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?

Round-robin | |

First in, first out | |

Multilevel queue scheduling | |

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

address | |

locator | |

operation code | |

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?

Dispatcher | |

Interrupt | |

Scheduler | |

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?

Memory is the locality in the system | |

Cache memory is local memory | |

Main memory is local memory | |

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

->Spatial locality

->Temporal locality

Question 9 |

The database does not have the component

user data | |

metadata | |

reports | |

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

eliminates | |

reduces | |

increases | |

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

first normal form | |

second normal form | |

third normal form | |

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

metalanguage | |

data definition language | |

procedural query language | |

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?

Updation | |

Addition | |

Deletion | |

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.

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

log _{2}(n) - 1 | |

log _{2}(n)+ 1 | |

log _{2}(n) - 2 | |

log _{2}(n) - 4 |

Question 15 |

Which is not true for a B-tree of order m?

Leaf nodes must be at the same level | |

All the key values within a node must be in ascending order | |

All non-leaf nodes must have at least m/2 children | |

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?

They can be represented by using adjacency list | |

They can be represented by using adjacency matrix | |

They can be represented by using incidence matrix | |

Addition of a node has complexity O(n) |

Question 16 Explanation:

Question 17 |

A program written in C is converted into machine language using

interpreter | |

compiler | |

editor | |

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];

arr and &arr[0] point to the address of first element | |

arr[0] is equivalent to *arr | |

Both (a) and (b) are correct | |

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

120 | |

nNum(5) | |

4! | |

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

no borrow from bablu or rohit | |

no bablu rohit borrow or from | |

Both are correct depending on the process | |

None of the above |

Question 20 Explanation:

The output is ohitrrow froablu or

Question 21 |

The software interrupts in 8085 are in numbers

5 | |

8 | |

12 | |

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

7 | |

5 | |

3 | |

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 16-bit register microprocessor used to indicate the beginning of stack memory | |

a register used to decode and execute 16-bit arithmetic expression | |

first memory location used to store a subroutine address | |

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?

Register select | |

Chip select | |

Both of the above
| |

None of the above |

Question 25 |

The network layer does not have the functionality

routing | |

inter-networking | |

congestion control | |

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

socket | |

pipe | |

port | |

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

application to application | |

process to process | |

node to node | |

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.

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

propagation delay | |

queuing delay | |

transmission delay | |

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

propagation delay | |

queuing delay | |

transmission delay | |

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

f(x) will be integral part of x | |

f(x) will be fractional part of x | |

f(x) will always be zero | |

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) = x^{2}+ 1. Then the function f∘g is(x^2+2)^2 | |

(x^2+1)^2 | |

(x^2+1)^2 (x^2+1) | |

None of the above |

Question 31 Explanation:

Question 32 |

The variance of the binomial distribution with parameters n and p is given by

p | |

np | |

p(1 - p) | |

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

λ | |

1/λ | |

λ ^{2} | |

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

λ | |

1/λ
| |

1 | |

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?

Normal | |

Bernoulli | |

Binomial | |

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.

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

E(x) = m /(m-n) | |

E(x) = m /(m+n) | |

E(x) = n /(m+n) | |

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:

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

Bayes process | |

functional process | |

independent limited process | |

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

E(x)=pq/μ | |

E(x)=μ/np | |

E(x)=n/μ | |

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

0 | |

1/2 | |

1/3 | |

2/3 |

Question 39 Explanation:

Question 40 |

The covariance cov(X, Y) of two independent random variables X and Y is

0 | |

1 | |

-1 | |

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

combination | |

sample point | |

compound event | |

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

teacher-centric
| |

student-centric | |

general-centric | |

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

interpersonal | |

mass communication | |

group communication | |

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

argument | |

information | |

ideas | |

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

initiate discussion and participate
| |

import information | |

ask students to read books | |

suggest good reference material |

Question 46 |

Teacher’s most precious asset is

his/her job | |

student’s faith | |

prejudice | |

books |

Question 47 |

The most important thing in the behaviour of a teacher is

dominance | |

discipline | |

sympathy | |

patience |

Question 48 |

Which of the following is not research?

Exploratory research study | |

Descriptive research study | |

Diagnostic research study | |

Populistic research study |

Question 49 |

Successful teacher is one who can

teach subject text properly | |

describe the subject | |

encourage the students | |

help in evaluation |

Question 50 |

The number of significant digits in the number 4.3700×10Ms

^{-2}is3 | |

4 | |

5 | |

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

applied research | |

fundamental research | |

conceptual research | |

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

0.0062% | |

0.062% | |

0.62% | |

6.2% |

Question 52 Explanation:

Question 53 |

ANOVA stands for

Analysis of Vector | |

Analysis of Validation | |

Analysis of Variance | |

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

logical | |

replicable | |

systematic | |

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

quantitative research | |

qualitative research | |

fundamental research | |

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

is increased | |

is decreased | |

is not affected | |

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

3 | |

5 | |

9 | |

-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?

Chebyshev | |

Statutory | |

Testory | |

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

discrete random variable | |

continuous random variable | |

mixed-type random variable | |

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?

Confirmatory research design | |

Descriptive and diagnostic research design | |

Exploratory research design | |

Hypothesis-testing research design |

Question 61 |

0 | |

∞ | |

1 | |

f(x) + 1 |

Question 61 Explanation:

There are 61 questions to complete.