TNPSC-2012-Polytechnic-CS

Question 1
Which of the following computers is least powerful?
A
Mini
B
Micro
C
Mainframe
D
Super
Question 1 Explanation: 
Micro computer is the least powerful computer and super computer is the most powerful computer.
Question 2
The technique which repeatedly uses the same block of internal storage during different stages of problem is called
A
Overlay
B
Overlapping
C
Swapping
D
Reuse
Question 2 Explanation: 
In a general computing sense, overlaying means "the process of transferring a block of program code or other data into main memory, replacing what is already stored". Overlaying is a programming method that allows programs to be larger than the computer's main memory.
Question 3
The number of instructions needed to add n numbers and store the result in memory using only one address instruction is
A
n
B
n+1
C
n-1
D
independent of n
Question 3 Explanation: 
At first instruction we will load the first no. in accumulator and then from second instruction we will add remaining n-1 no. using accumulator. Till now n instruction is used. And finally we will use one more instruction to store the result back to memory. So in total n+1 instruction is required.
Question 4
The most relevant addressing mode to write position independent code is
A
Direct mode
B
Indirect mode
C
Relative mode
D
Indexed mode
Question 4 Explanation: 
Relative mode is the most relevant addressing mode to write position independent code.
Indexed mode is for arrays and structure.
Indirect mode is used for pointers.
Question 5
The CPU of a computer takes instruction from the memory and executes them. This process is called
A
Load cycle
B
Time sequences
C
Fetch-execute cycle
D
Clock cycle
Question 5 Explanation: 
The process in which a CPU of a computer takes instruction from memory and executes them is called fetch-execute cycle.
Question 6
A five figure number is formed by the digits 0, 1, 2, 3, 4 without repetition. Then probability that the number formed is divisible by 4 in
A
3/15
B
5/16
C
7/16
D
9/16
Question 7
If A and B be sets with cardinalities m and n respectively, then number of one-one mappings (injections) from A to B, when m < n, is
A
mn
B
nPm
C
nCm
D
None of these
Question 7 Explanation: 
The formula for above given question is nPm.
Question 8
The set of all nth roots of unity under multiplication of complex numbers form a/an
A
Semi-group with identity
B
Communicative semi groups with identity
C
Group
D
Abelian group
Question 8 Explanation: 
More generally, if C is a group and z∈C with zn = 1, where 1 is the identity of C, then G = {1,z,z2,...,zn-1} is a group (actually, a subgroup of C).
Indeed:
• Closure: zjzk = zj+k = zr ∈ G, where r = (j+k) mod n.
• Associativity: comes from C.
• Identity: 1 ∈ G by definition, and 1 is the identity of C.
• Inverse: zjzn-j = 1.
• Commutativity: zjzk = zj+k = zk+j = zkzj.
Question 9
How many 10 digit numbers can be written by using the digits 1 and 2?
A
10 C1 + 9 C2
B
210
C
10 C2
D
10 1
Question 9 Explanation: 
For each digit we have two choices ‘1 or 2’. So no. of possible 10 digits nos.
2*2*2*2*2*2*2*2*2*2 = 210
Question 10
T is a graph with n vertices. T is connected and has exactly n – 1 edges. Then
A
T is a tree
B
T contains no cycles
C
Every pair of vertices in T is connected by exactly one path
D
Addition of a new edge will create a cycle
Question 10 Explanation: 
Any graph with n vertices and n-1 edges which is connected will definitely be a tree.
Question 11
Eigenvectors of a real symmetric matrix corresponding to different eigenvalues are
A
Orthogonal
B
Singular
C
Non-singular
D
None of these
Question 11 Explanation: 
Eigen-vectors of a real symmetric matrix corresponding to different eigenvalues are orthogonal to each other.
Question 12
If L1 and L2 are context free language and R is a regular set. Which one of the languages below is not necessarily a context free language?
A
L1L2
B
L1∩L2
C
L1∪R
D
L1∪L2
Question 12 Explanation: 
Context free language is not closed under intersection. Hence B is the correct option.
Question 13
CSG can be recognized by
A
push-down automata
B
2 way linear bounded automaton
C
finite state automata
D
none of these
Question 13 Explanation: 
Context sensitive grammar can be recognized by linear bounded automata.
Question 14
Consider the following grammar:
S → Ax |By
A → By|Cw
B → x|Bw
C → y 
Which of the regular expressions describes the same set of strings as the grammar?
A
xw+y+xw*yx+ywx
B
xwy+xw*xy*ywx
C
xw*y+xw*yx+ywx
D
xwxy+xww*yywx
Question 14 Explanation: 
Option A do not contain xy which is generated by the grammar.
Option B do not contain xy which is generated by the grammar.
Option C do not contain xy which is generated by the grammar.
Question 15
Recursively enumerable languages are not closed under
A
Union
B
Intersection
C
Complementation
D
Concatenation
Question 15 Explanation: 
Recursively enumerable language are not closed under complementation.
Question 16
Turing machine is more powerful than FMs because
A
Tape movement is confined to one direction
B
It has no finite state
C
It has the capability to remember arbitrarily long sequences of input symbols
D
None of these
Question 16 Explanation: 
Turing machines is more powerful than finite machines because it has the capability to remember arbitrarily long sequences of input symbols.
Question 17
Which of the following statements is wrong?
A
The language accepted by finite automata is the languages denoted by regular expressions.
B
For every DFA there is a regular expression denoting its language
C
For a regular expression r, there does not exist any NFA with transit that accepts L(r)
D
None of these
Question 17 Explanation: 
NFA, DFA and regular expression are equal in power. So for every regular expression there exists DFA and NFA.
Question 18
Can a DFA simulate NFA?
A
No
B
Yes
C
Sometimes
D
Depends of NFA
Question 18 Explanation: 
DFA has equal power as NFA.
Question 19
Let a and b be the regular expressions, then (a*∪b*)* is not equivalent to
A
(a∪b)*
B
(b*∪a*)*
C
(b∪a)*
D
(a∪b)
Question 19 Explanation: 
The given regular expression is not equal to option D.
Question 20
FDDI is a
A
Ring network
B