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