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440+ Discrete Mathematics Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Computer Science Engineering (CSE) .

201.

Let (A7, ⊗7)=({1, 2, 3, 4, 5, 6}, ⊗7) is a group. It has two sub groups X and Y. X={1, 3, 6}, Y={2, 3, 5}. What is the order of union of subgroups?

A. 65
B. 5
C. 32
D. 18
Answer» B. 5
202.

A relation (34 × 78) × 57 = 57 × (78 × 34) can have                      property.

A. distributive
B. associative
C. commutative
D. closure
Answer» B. associative
203.

B1: ({0, 1, 2….(n-1)}, xm) where xn stands for “multiplication-modulo-n” and B2: ({0, 1, 2….n}, xn) where xn stands for “multiplication-modulo-m” are the two statements. Both B1 and B2 are considered to be                      

A. groups
B. semigroups
C. subgroups
D. associative subgroup
Answer» B. semigroups
204.

If group G has 65 elements and it has two subgroups namely K and L with order 14 and 30. What can be order of K intersection L?

A. 10
B. 42
C. 5
D. 35
Answer» C. 5
205.

Consider the binary operations on X, a*b = a+b+4, for a, b ∈ X. It satisfies the properties of                

A. abelian group
B. semigroup
C. multiplicative group
D. isomorphic group
Answer» A. abelian group
206.

Let * be the binary operation on the rational number given by a*b=a+b+ab. Which of the following property does not exist for the group?

A. closure property
B. identity property
C. symmetric property
D. associative property
Answer» B. identity property
207.

A group G, ({0}, +) under addition operation satisfies which of the following properties?

A. identity, multiplicity and inverse
B. closure, associativity, inverse and identity
C. multiplicity, associativity and closure
D. inverse and closure
Answer» B. closure, associativity, inverse and identity
208.

If (M, *) is a cyclic group of order 73, then number of generator of G is equal to              

A. 89
B. 23
C. 72
D. 17
Answer» C. 72
209.

The set of even natural numbers, {6, 8, 10, 12,..,} is closed under addition operation. Which of the following properties will it satisfy?

A. closure property
B. associative property
C. symmetric property
D. identity property
Answer» A. closure property
210.

A non empty set A is termed as an algebraic structure                  

A. with respect to binary operation *
B. with respect to ternary operation ?
C. with respect to binary operation +
D. with respect to unary operation –
Answer» A. with respect to binary operation *
211.

An algebraic structure                    is called a semigroup.

A. (p, *)
B. (q, +, *)
C. (p, +)
D. (+, *)
Answer» A. (p, *)
212.

Condition for monoid is                      

A. (a+e)=a
B. (a*e)=(a+e)
C. a=(a*(a+e)
D. (a*e)=(e*a)=a
Answer» D. (a*e)=(e*a)=a
213.

A monoid is called a group if                

A. (a*a)=a=(a+c)
B. (a*c)=(a+c)
C. (a+c)=a
D. (a*c)=(c*a)=e
Answer» D. (a*c)=(c*a)=e
214.

Matrix multiplication is a/an                     property.

A. commutative
B. associative
C. additive
D. disjunctive
Answer» B. associative
215.

How many properties can be held by a group?

A. 2
B. 3
C. 5
D. 4
Answer» C. 5
216.

A cyclic group is always                    

A. abelian group
B. monoid
C. semigroup
D. subgroup
Answer» A. abelian group
217.

{1, i, -i, -1} is                      

A. a commutative subgroup
B. a lattice
C. a trivial group
D. a monoid
Answer» C. a trivial group
218.

Let K be a group with 8 elements. Let H be a subgroup of K and H<K. It is known that the size of H is at least 3. The size of H is

A. semigroup                      
B. subgroup
C. cyclic group
D. abelian group
Answer» C. cyclic group
219.

                     is not necessarily a property of a Group.

A. commutativity
B. existence of inverse for every element
C. existence of identity
D. associativity
Answer» A. commutativity
220.

A group of rational numbers is an example of                      

A. a subgroup of a group of integers
B. a subgroup of a group of real numbers
C. a subgroup of a group of irrational numbers
D. a subgroup of a group of complex numbers
Answer» B. a subgroup of a group of real numbers
221.

Intersection of subgroups is a

A. group
B. subgroup
C. semigroup
D. cyclic group
Answer» B. subgroup
222.

What is a circle group?

A. a subgroup complex numbers having magnitude 1 of the group of nonzero complex elements
B. a subgroup rational numbers having magnitude 2 of the group of real elements
C. a subgroup irrational numbers having magnitude 2 of the group of nonzero complex elements
D. a subgroup complex numbers having magnitude 1 of the group of whole numbers
Answer» A. a subgroup complex numbers having magnitude 1 of the group of nonzero complex elements
223.

A normal subgroup is                          

A. a subgroup under multiplication by the elements of the group
B. an invariant under closure by the elements of that group
C. a monoid with same number of elements of the original group
D. an invariant equipped with conjugation by the elements of original group
Answer» D. an invariant equipped with conjugation by the elements of original group
224.

Two groups are isomorphic if and only if                      is existed between them.

A. homomorphism
B. endomorphism
C. isomorphism
D. association
Answer» C. isomorphism
225.

a * H is a set of            coset.

A. right
B. left
C. sub
D. semi
Answer» B. left
226.

a * H = H * a relation holds if                      

A. h is semigroup of an abelian group
B. h is monoid of a group
C. h is a cyclic group
D. h is subgroup of an abelian group
Answer» D. h is subgroup of an abelian group
227.

Lagrange’s theorem specifies                      

A. the order of semigroup is finite
B. the order of the subgroup divides the order of the finite group
C. the order of an abelian group is infinite
D. the order of the semigroup is added to the order of the group
Answer» B. the order of the subgroup divides the order of the finite group
228.

A function is defined by f(x)=2x and f(x + y) = f(x) + f(y) is called                            

A. isomorphic
B. homomorphic
C. cyclic group
D. heteromorphic
Answer» A. isomorphic
229.

An isomorphism of a group onto itself is called                          

A. homomorphism
B. heteromorphism
C. epimorphism
D. automorphism
Answer» D. automorphism
230.

The elements of a vector space form a/an                          under vector addition.

A. abelian group
B. commutative group
C. associative group
D. semigroup
Answer» A. abelian group
231.

A set of representatives of all the cosets is called                    

A. transitive
B. reversal
C. equivalent
D. transversal
Answer» D. transversal
232.

Which of the following statement is true?

A. the set of all rational negative numbers forms a group under multiplication
B. the set of all matrices forms a group under multiplication
C. the set of all non-singular matrices forms a group under multiplication
D. the set of matrices forms a subgroup under multiplication
Answer» C. the set of all non-singular matrices forms a group under multiplication
233.

How many different non-isomorphic Abelian groups of order 8 are there?

A. 5
B. 4
C. 2
D. 3
Answer» C. 2
234.

Consider the set B* of all strings over the alphabet set B = {0, 1} with the concatenation operator for strings                  

A. does not form a group
B. does not have the right identity element
C. forms a non-commutative group
D. forms a group if the empty string is removed from
Answer» A. does not form a group
235.

All groups satisfy properties

A. g-i to g-v
B. g-i to g-iv
C. g-i to r-v
D. r-i to r-v
Answer» B. g-i to g-iv
236.

An Abelian Group satisfies the properties

A. g-i to g-v
B. g-i to r-iv
C. g-i to r-v
D. r-i to r-v
Answer» A. g-i to g-v
237.

A Ring satisfies the properties

A. r-i to r-v
B. g-i to g-iv
C. g-i to r-v
D. g-i to r-iii
Answer» D. g-i to r-iii
238.

A Ring is said to be commutative if it also satisfies the property

A. r-vi
B. r-v
C. r-vii
D. r-iv
Answer» D. r-iv
239.

An ‘Integral Domain’ satisfies the properties

A. g-i to g-iii
B. g-i to r-v
C. g-i to r-vi
D. g-i to r-iii
Answer» C. g-i to r-vi
240.

a.(b.c) = (a.b).c is the representation for which property?

A. g-ii
B. g-iii
C. r-ii
D. r-iii
Answer» A. g-ii
241.

a(b+c) = ac+bc is the representation for which property?

A. g-ii
B. g-iii
C. r-ii
D. r-iii
Answer» D. r-iii
242.

For the group Sn of all permutations of n distinct symbols, what is the number of elements in Sn?

A. n
B. n-1
C. 2n
D. n!
Answer» D. n!
243.

Does the set of residue classes (mod 3) form a group with respect to modular addition?

A. yes
B. no
C. can’t say
D. insufficient data
Answer» A. yes
244.

Does the set of residue classes (mod 3) form a group with respect to modular addition?

A. yes
B. no
C. can’t say
D. insufficient data
Answer» B. no
245.

The less-than relation, <, on a set of real numbers is              

A. not a partial ordering because it is not asymmetric and irreflexive equals antisymmetric
B. a partial ordering since it is asymmetric and reflexive
C. a partial ordering since it is antisymmetric and reflexive
D. not a partial ordering because it is not antisymmetric and reflexive
Answer» A. not a partial ordering because it is not asymmetric and irreflexive equals antisymmetric
246.

If the longest chain in a partial order is of length l, then the partial order can be written as            disjoint antichains.

A. l2
B. l+1
C. l
D. ll
Answer» C. l
247.

Suppose X = {a, b, c, d} and π1 is the partition of X, π1 = {{a, b, c}, d}. The number of ordered pairs of the equivalence relations induced by                      

A. 15
B. 10
C. 34
D. 5
Answer» B. 10
248.

The inclusion of              sets into R = {{1, 2}, {1, 2, 3}, {1, 3, 5}, {1, 2, 4}, {1, 2, 3, 4, 5}} is necessary and sufficient to make R a complete lattice under the partial order defined by set containment.

A. {1}, {2, 4}
B. {1}, {1, 2, 3}
C. {1}
D. {1}, {1, 3}, {1, 2, 3, 4}, {1, 2, 3, 5}
Answer» C. {1}
249.

Consider the set N* of finite sequences of natural numbers with a denoting that sequence a is a prefix of sequence b. Then, which of the following is true?

A. every non-empty subset of has a greatest lower bound
B. it is uncountable
C. every non-empty finite subset of has a least upper bound
D. every non-empty subset of has a least upper bound
Answer» A. every non-empty subset of has a greatest lower bound
250.

A partial order ≤ is defined on the set S = {x, b1, b2, … bn, y} as x ≤ bi for all i and bi ≤ y for all i, where n ≥ 1. The number of total orders on the set S which contain the partial order ≤ is              

A. n+4
B. n2
C. n!
D. 3
Answer» C. n!

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