Nov 2017 Paper III Part 1

Introduction

The National Eligibility Test (NET) is conducted on behalf of the University Grants Commission (UGC) to determine the eligibility of Indian nationals for the Eligibility of Assistant Professorship, Junior Research Fellowship, or both for Indian Universities and Colleges. In this blog, we will go through the questions and solutions of June 2014 Paper-II of UGC - NET EXAM. In this blog, we have covered questions from 1 - 25. For questions from 26 - 50 refer  Nov 2017  Paper III Part 2  and from 51 - 75 refer.

Questions

1. In an 8085 microprocessor, which of the following flag(s) is (are) affected by an arithmetic operation?

(1) AC flag Only

(2) CY flag Only

(3) Z flag Only

(4) AC, CY, Z flags

 

ANS - (4)

Solution - All the Carry flag(CY), Auxiliary Carry flag(AC), and Zero Flag(Z) are affected when an arithmetic operation is performed.
 

2. In an 8085 microprocessor, the address bus is of .................... bits.

(1) 4

(2) 8

(3) 16

(4) 32
 

ANS - (3)

Solution - In the 8085 microprocessor, the address bus is of 16 bits.
 

3. In the architecture of the 8085 microprocessor match the following:

List - I

(a) Processing unit

(b) Instruction unit

(c) Storage and Interface unit

List - II

(i) Interrupt

(ii) General purpose Register

(iii) ALU

(iv) Timing and Control

Code :

    (a) (b) (c)

(1) (iv) (i) (ii)

(2) (iii) (iv) (ii)

(3) (ii) (iii) (i)

(4) (i) (ii) (iv)

 

ANS - (2)

Solution - 

Processing Unit -> ALU

Instruction Unit ->Timing and Control

Storage and Interface unit -> General Purpose Register
 

4. Which of the following addressing mode is best suited to access elements of an array of contiguous memory locations?

(1) Indexed addressing mode

(2) Base Register addressing mode

(3) Relative address mode

(4) Displacement mode

 

ANS - (1)

Solution - Indexed addressing mode is best suited for accessing an array in a contiguous memory location.
 

5. Which of the following is the correct statement?

(1) In memory-mapped I/O, the CPU can manipulate I/O data residing in interface registers that are not used to manipulate memory words.

(2) The isolated I/O method isolates memory and I/O addresses so that the memory address range is not affected by interface address assignment.

(3) In an asynchronous serial data transfer, the two units share a common clock.

(4) In the synchronous serial transmission of data, the two units have different clocks

 

ANS - (2)

Solution - In isolated I/O, unique 8-bit addresses are allocated to the I/O devices. They can be accessed using instructions like IN and OUT.

 

6. A micro-instruction format has a micro-ops field which is divided into three subfields, F1, F2, and F3, each having seven distinct micro-operations, condition field CD for four status bits, and branch field BR having four options used in conjunction with address field ADF. The address space is of 128 memory locations. The size of micro-instruction is:

(1) 17 bits

(2) 20 bits

(3) 24 bits

(4) 32 bits

 

ANS - (2)

Solution - There are 3 fields in the microinstruction.

1. Micro operation fields = F1, F2, F3
2. CD for status bits
3. BR in conjunction with ADF, i.e., we need to multiply a possible number of branch fields with the Address field.

F1, F2, and F3 each have 7 microoperations.

# of bits to represent it

log27+log27+log 27=3+3+3=9

CD for status bits=log24=2

 

BR in conjunction with ADF=log2(4×128)=9

Total bits=9+2+9=20 bits.

 

7. Consider the following four schedules due to three transactions (indicated by the subscript) using read and write on a data item X, denoted by r(X) and w(X), respectively. Which one of them is conflict serializable?

S1 : r1(X); r2(X); w1(X); r3(X); w2(X)

S2 : r2(X); r1(X); w2(X); r3(X); w1(X)

S3 : r3(X); r2(X); r1(X); w2(X); w1(X)

S4 : r2(X); w2(X); r3(X); r1(X); w1(X)

(1) S1

(2) S2

(3) S3

(4) S4

 

ANS - (4)

Solution - Only the graph will be acyclic for option (D). Hence (D) is CSS.

 

8. Suppose a database schedule S involves transactions T1, T2, ............., Tn. Consider 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?

(1) Topological order

(2) Depth-first order

(3) Breadth-first order

(4) Ascending order of transaction indices

 

ANS - (1)

Solution - Topological sort of any cyclic graph is not possible. Thus topological sort guarantees the graph to be serializable. Option D is not valid because a transaction with more indices might have to come before a lower one.

 

9. If every non-key attribute is functionally dependent on the primary key, then the relation is in ....................

(1) First normal form

(2) Second normal form

(3) Third normal form

(4) Fourth normal form

 

ANS - (3)

Solution - 

1. 1 NF – A relation R is in first normal form (1NF) if all underlying domains contain atomic values only.
2. 2 NF – A relation R is in second normal form (2NF) only if it is in 1NF, and every non-key attribute is entirely dependent on the primary key.
3. 3 NF – A relation R is in third normal form (3NF) only if it is in 2NF, and every non-key attribute is non-transitively dependent on the primary key.
4. BCNF – A relation R is in Boyce-Codd normal form (BCNF) if and only if every determinant is a candidate key.
    

10. Consider a relation R (A, B, C, D, E, F, G, H), where each attribute is atomic, and the following functional dependencies exist.

CH → G

A → BC

B → CFH

E → A

F → EG

The relation R is ....................

(1) in 1NF but not in 2NF

(2) in 2NF but not in 3NF

(3) in 3NF but not in BCNF

(4) in BCNF

 

ANS - (1)

Solution - A+ (closure of A) → All attributes except D.

Similarly, for other keys, we can find closure, but D can't be derived from any key, and it must be added to all keys to be derived from. That's why this relation is in 1NF. Since there is partial dependency, this relation is not in 2NF.
 

11. Given two relations, R1(A, B) and R2(C, D), the result of the following query.

Select distinct A, B from R1, R2

is guaranteed to be the same as R1 provided one of the following conditions is satisfied.

(1) R1 has no duplicates, and R2 is empty.

(2) R1 has no duplicates, and R2 is non-empty.

(3) Both R1 and R2 have no duplicates.

(4) R2 has no duplicates, and R1 is non-empty.

 

ANS - (2)

Solution - 

Select A, B

From R1, R2 :

In this query, first, we will take the cartesian product of R1, R2 (R2 must be non-empty)for this 0- R2 then select distinct A, B from cartesian product of R1, R2 (for A, B being distinct there should not be any duplicate A, B).

And

Select A, B

From R2

For this query A, B → , No duplicates A, B.

By combining conditions for both queries, we will get the proper condition.

 

12. Consider a schema R(A, B, C, D) and the following functional dependencies.

A → B

B → C

C → D

D → B

Then the decomposition of R into R1(A, B), R2(B, C), and R3(B, D) are..................

(1) Dependency preserving and lossless join.

(2) Lossless join but not dependency preserving.

(3) Dependency preserving but not lossless join.

(4) Not dependency preserving and not lossless join.

 

ANS - (1)

Solution - Decomposition of R into R1 and R2 is a dependency preserving decomposition if the closure of functional dependencies after decomposition is the same as the closure of FDs before decomposition.

A simple way is to check whether we can derive all the original FDs from the FDs present after decomposition.

In the above question, R(A, B, C, D) is decomposed into R1 (A, B) and R2(C, D), and there are only two FDs A -> B and C -> D. So, the decomposition is dependency preserving.

Lossless-Join Decomposition:

Decomposition of R into R1 and R2 is a lossless-join decomposition if at least one of the following functional dependencies is in F+ (Closure of functional dependencies)

   R1 ∩ R2 → R1

   OR

   R1 ∩ R2 → R2

 

In the above question R(A, B, C, D) is decomposed into R1 (A, B) and R2(C, D), and R1 ∩ R2 is empty. So, the decomposition is not lossless.

 

13. Which of the following is not a component of the Memory tube display?

(1) Flooding gun

(2) Collector

(3) Ground

(4) Liquid Crystal
 

ANS - (4)

Solution - Liquid Crystal is not a component of the Memory tube display.

 

14. Which of the following is not true in the case of Oblique Projections?

(1) Parallel projection rays are not perpendicular to the viewing plane.

(2) Parallel lines in space appear parallel on the final projected image.

(3) Used exclusively for pictorial purposes rather than formal working drawings.

(4) Projectors are always perpendicular to the plane of projection.

 

ANS - (4)

Solution - Projectors are always perpendicular to the plane of projection is not true in the case of Oblique Projections.

 

15. With respect to CRT, the horizontal retrace is defined as :

(1) The path an electron beam takes when returning to the left side of the CRT.

(2) The path an electron beam takes when returning to the right side of the CRT.

(3) The technique of turning the electron beam off while retracing.

(4) The technique of turning the electron beam on/off while retracing.

 

ANS - (1)

Solution - In computer graphics, Horizontal Retrace is defined as The path an electron beam takes when returning to the left side of the CRT.

 

16. Find the equation of the circle x2+y2=1 in terms of x'y' coordinates, assuming that the xy coordinate system results from a scaling of 3 units in the x' direction and 4 units in the y' direction.

(1) 3(x')2 + 4(y')2 = 1

(2) (x'/3)2 + (y'/4)2 = 1

(3) (3x')2 + (4y')2 = 1

(4) 1/3(x')2 + 1/4(y')2 = 1

 

ANS - (2)

Solution - Let f[x,y]==0 be the equation for a curve in rectangular coordinates. To scale the curve by s, the new equation would be: f[x/s, y/s]==0

Let f[θ,r]==0 be the equation for a curve in polar coordinate. To scale it by s, the new formula is f[r/s,θ]==0.

Replace x to x'/3 and y to y'/4, so the answer will be an option (2).

 

17. Find the normalization transformation that maps a window whose lower-left corner is at (1, 1) and upper right corner is at (3, 5) onto a viewport that is the entire normalized device screen.

 

ANS - (1)

Solution - The window parameters are Wxmin = 1, Wymin = 1, Wxmax = 3, Wymax = 5

Viewport parameters are Vxmin = 0, Vymin = 0, Vxmax = 1, Vymax = 1

Hence Sx = ½ and Sy = ¼

So N = Option (1).
 

18. The three aspects of Quantization, programmers generally concerned with are:

(1) Coding error, Sampling rate, and Amplification

(2) Sampling rate, Coding error, and Conditioning

(3) Sampling rate, Aperture time, and Coding error

(4) Aperture time, Coding error, and Strobing

 

ANS - (3)

Solution - The three aspects of quantization, programmers generally concerned with are

1. Sampling rate
2. Aperture time
3. Coding error
    

19. The logic of the pumping lemma is an example of ....................

(1) iteration

(2) recursion

(3) the divide and conquer principle

(4) the pigeon - hole principle

 

ANS - (4)

Solution - The logic of the pumping lemma is an example of the pigeon-hole principle.

 

20. Heap allocation is required for languages that :

(1) use dynamic scope rules

(2) support dynamic data structures

(3) support recursion

(4) support recursion and dynamic data structures

 

ANS - (2)

Solution - Heap allocation is required for languages that support dynamic data structures.

 

21. Pumping lemma for regular language is generally used for proving:

(1) whether two given regular expressions are equivalent

(2) a given grammar is ambiguous

(3) a given grammar is regular

(4) a given grammar is not regular

 

ANS - (4)

Solution - Pumping lemma is used to prove a language is regular or not.

 

22. Which of the following problems is undecidable?

(1) To determine if two finite Automata are equivalent

(2) Membership problem for context free grammar

(3) Finiteness problem for finite automata

(4) Ambiguity problem for context free grammar

ANS - (4)

Solution - Ambiguity problem for context free grammar is undecidable.

 

23. Finite state machine can recognize language generated by ....................

(1) Only context free grammar

(2) Only context sensitive grammar

(3) Only regular grammar

(4) any unambiguous grammar

 

ANS - (3)

Solution - Finite state machines can recognize language generated by regular grammar only.

 

24. The language L = {ai b ci | i ≥ 0} over the alphabet {a, b, c} is:

(1) a regular language.

(2) not a deterministic context free language but a context free language.

(3) recursive and is a deterministic context free language.

(4) not recursive.

 

ANS - (3)

Solution - Given language has equal number of a in the beginning as the number of c in the end which makes it context free language.

Simultaneously, they are separated by b which makes the language deterministic.

So, the language is DCFL and as DCFL is the subset of recursive languages it is recursive too.

 

25. Suppose we want to download text documents at the rate of 100 pages per second. Assume that a page consists of an average of 24 lines with 80 characters in each line. What is the required bit rate of the channel?

(1) 192 kbps

(2) 512 kbps

(3) 1.248 Mbps

(4) 1.536 Mbps

 

ANS - (4)

Solution - We have 100 pages, each page has 24 lines and in each line there are 80 characters and each character is of 8 bits.

Now we have to calculate no of bits can be downloaded:

ie.

Downloading rate = 100 pages 

= 100 pages *24 line * 80 character * 8 bits

= 1536000 bits per second

ie 1.536 Mbps.