Friday, September 18, 2020

Database Systems MCQ

 Q.1 Which of the following relational algebra operations do not require the participating tables to be union-compatible?

(A) Union 

(B) Intersection

(C) Difference 

(D) Join

Ans: (D)


Q.2 Which of the following is not a property of transactions?

(A) Atomicity 

(B) Concurrency

(C) Isolation 

(D) Durability

Ans: (B)


Q.3 Relational Algebra does not have

(A) Selection operator. 

(B) Projection operator.

(C) Aggregation operators. 

(D) Division operator.

Ans: (C)


Q.4 Checkpoints are a part of

(A) Recovery measures. 

(B) Security measures.

(C) Concurrency measures. 

(D) Authorization measures.

Ans: (A)


Q.5 Tree structures are used to store data in

(A) Network model. 

(B) Relational model.

(C) Hierarchical model. 

(D) File based system.

Ans: (C)


Q.6 The language that requires a user to specify the data to be retrieved without specifying exactly how to get it is

(A) Procedural DML. 

(B) Non-Procedural DML.

(C) Procedural DDL. 

(D) Non-Procedural DDL.

Ans: (B)


Q.7 Precedence graphs help to find a

(A) Serializable schedule. 

(B) Recoverable schedule.

(C) Deadlock free schedule. 

(D) Cascadeless schedule.

Ans: (A)


Q.8 The rule that a value of a foreign key must appear as a value of some specific table is called a

(A) Referential constraint. 

(B) Index.

(C) Integrity constraint. 

(D) Functional dependency.

Ans: (A) The rule that a value of a foreign key must appear as a value of some specific table is called a referential constraint. (Referential integrity constraint is concerned with foreign key)


Q.9 The clause in SQL that specifies that the query result should be sorted in ascending or descending order based on the values of one or more columns is

(A) View 

(B) Order by

(C) Group by 

(D) Having

Ans: (B) The clause in SQL that specifies that the query result should be sorted in ascending or descending order based on the values of one or more columns is ORDER BY. (ORDER BY clause is used to arrange the result of the SELECT statement)


Q.10 What is a disjoint less constraint?

(A) It requires that an entity belongs to no more than one level entity set.

(B) The same entity may belong to more than one level.

(C) The database must contain an unmatched foreign key value.

(D) An entity can be joined with another entity in the same level entity set.

Ans: (A) Disjoint less constraint requires that an entity belongs to no more than one level entity set. (Disjoint less constraint means that an entity can be a member of at most one of the subclasses of the specialization.)


Q.11 According to the levels of abstraction, the schema at the intermediate level is called

(A) Logical schema. 

(B) Physical schema.

(C) Subschema. 

(D) Super schema.

Ans: According to the levels of abstraction, the schema at the intermediate level is called conceptual schema. (Note: All the options given in the question are wrong.)


Q.12 It is an abstraction through which relationships are treated as higher level entities

(A) Generalization. 

(B) Specialization.

(C) Aggregation. 

(D) Inheritance.

Ans: (C ) It is an abstraction through which relationships are treated as higher level entities Aggregation. (In ER diagram, aggregation is used to represent a relationship as an entity set.)


Q.13 A relation is in ____________ if an attribute of a composite key is dependent on an attribute of other composite key.

(A) 2NF 

(B) 3NF

(C) BCNF 

(D) 1NF

Ans: (B) A relation is in 3 NF if an attribute of a composite key is dependent on an attribute of other composite key. (If an attribute of a composite key is dependent on an attribute of other composite key then the relation is not in BCNF, hence it has to be decomposed.)


Q.14 What is data integrity?

(A) It is the data contained in database that is non redundant.

(B) It is the data contained in database that is accurate and consistent.

(C) It is the data contained in database that is secured.

(D) It is the data contained in database that is shared.

Ans: (B) (Data integrity means that the data must be valid according to the given constraints. Therefore, the data is accurate and consistent.)


Q.15 What are the desirable properties of a decomposition

(A) Partition constraint. 

(B) Dependency preservation.

(C) Redundancy. 

(D) Security.

Ans: (B) What are the desirable properties of a decomposition – dependency preserving. (Lossless join and dependency preserving are the two goals of the decomposition.)


Q.16 In an E-R diagram double lines indicate

(A) Total participation. 

(B) Multiple participation.

(C) Cardinality N. 

(D) None of the above.

Ans: (A)


Q.17 The operation which is not considered a basic operation of relational algebra is

(A) Join. 

(B) Selection.

(C) Union. 

(D) Cross product.

Ans: (A)


Q.18 Fifth Normal form is concerned with

(A) Functional dependency. 

(B) Multivalued dependency.

(C) Join dependency. 

(D) Domain-key.

Ans: (C)


Q.19 Block-interleaved distributed parity is RAID level

(A) 2. 

(B) 3

(C) 4. 

(D) 5.

Ans: (D)


Q.20 Immediate database modification technique uses

(A) Both undo and redo. 

(B) Undo but no redo.

(C) Redo but no undo. 

(D) Neither undo nor redo.

Ans: (A)


Q.21 In SQL the statement select * from R, S is equivalent to

(A) Select * from R natural join S. 

(B) Select * from R cross join S.

(C) Select * from R union join S. 

(D) Select * from R inner join S.

Ans: (B)


Q.22 Which of the following is not a consequence of concurrent operations?

(A) Lost update problem. 

(B) Update anomaly.

(C) Unrepeatable read. 

(D) Dirty read.

Ans: (B)


Q.23 As per equivalence rules for query transformation, selection operation distributes over

(A) Union. 

(B) Intersection.

(C) Set difference. 

(D) All of the above.

Ans: (D)


Q.24 The metadata is created by the

(A) DML compiler 

(B) DML pre-processor

(C) DDL interpreter 

(D) Query interpreter

Ans: (C)


Q.25 When an E-R diagram is mapped to tables, the representation is redundant for

(A) weak entity sets 

(B) weak relationship sets

(C) strong entity sets 

(D) strong relationship sets

Ans: (B)

Wednesday, September 16, 2020

Operating System MCQ

 Q.1 The field that contains a segment index or an internal index is called

(A) target datum 

(B) target offset

(C) segment field 

(D) fix dat

Ans: (A)


Q.2 A program in execution is called

(A) process 

(B) function

(C) CPU 

(D) Memory

Ans: (A)


Q.3 Jobs which are admitted to the system for processing is called

(A) long-term scheduling 

(B) short-term scheduling

(C) medium-term scheduling 

(D) queuing

Ans: (A)


Q.4 A set of techniques that allow to execute a program which is not entirely in memory is called

(A) demand paging 

(B) virtual memory

(C) auxiliary memory 

(D) secondary memory

Ans: (B)


Q.5 SSTF stands for

(A) Shortest-Seek-time-first scheduling 

(B) small – small-time-first

(C) simple-seek-time-first 

(D) small-simple-time-first scheduling

Ans: (A)


Q.6 Before proceeding with its execution, each process must acquire all the resources it needs is called

(A) hold and wait 

(B) No pre-emption

(C) circular wait 

(D) starvation

Ans: (A)


Q.7 Virtual memory is

(A) simple to implement

(B) used in all major commercial operating systems

(C) less efficient in utilization of memory

(D) useful when fast I/O devices are not available

Ans: (B)


Q.8 Relocation bits used by relocating loader are specified by

(A) Relocating loader itself 

(B) Assembler or Translator

(C) Macro processor 

(D) Both (A) and (B)

Ans: (B)


Q.9 Resolution of externally defined symbols is performed by

(A) Linker 

(B) Loader

(C) Compiler 

(D) Editor

Ans: (A)


Q.10 Relocatable programs

(A) cannot be used with fixed partitions

(B) can be loaded almost anywhere in memory

(C) do not need a linker

(D) can be loaded only at one specific location

Ans: (B)


Q.11 Page stealing

(A) is a sign of efficient system

(B) is taking page frames other working sets

(C) should be the tuning goal

(D) is taking larger disk spaces for pages paged out

Ans: (B)


Q.12 The total time to prepare a disk drive mechanism for a block of data to be read from is its

(A) latency

(B) latency plus transmission time

(C) latency plus seek time

(D) latency plus seek time plus transmission time

Ans: (C)


Q.13 To avoid race condition, the maximum number of processes that may be

simultaneously inside the critical section is

(A) zero 

(B) one

(C) two 

(D) more than two

Ans: (B)


Q.14 The memory allocation scheme subject to “external” fragmentation is

(A) segmentation 

(B) swapping

(C) pure demand paging 

(D) multiple fixed contiguous partitions

Ans: (A)


Q.15 Page fault frequency in an operating system is reduced when the

(A) processes tend to the I/O-bound

(B) size of pages is reduced

(C) processes tend to be CPU-bound

(D) locality of reference is applicable to the process

Ans: (D)


Q.16 In which of the following page replacement policies Balady’s anomaly occurs?

(A) FIFO 

(B) LRU

(C) LFU 

(D) NRU

Ans: (A)


Q.17 Which of the following are language processors?

(A) Assembler 

(B) Compiler

(C) Interpreter 

(D) All of the above

Ans: (D)


Q.18 Virtual memory can be implemented with

(A) Segmentation 

(B) Paging

(C) None 

(D) all of the above

Ans: (D)


Q.19 Recognition of basic syntactic constructs through reductions, this task is performed by

(A) Lexical analysis 

(B) Syntax analysis

(C) Semantic analysis 

(D) Structure analysis

Ans: (B)


Q.20 A grammar for a programming language is a formal description of

(A) Syntax 

(B) Semantics

(C) Structure 

(D) Code

Ans: (C)


Q.21 ___________ is a technique of temporarily removing inactive programs from the memory of computer system

(A) Swapping 

(B) Spooling

(C) Semaphore 

(D) Scheduler

Ans: (A)


Q.22 ___________ is a technique of improving the priority of process waiting in Queue for CPU allocation

(A) Starvation 

(B) Aging

(C) Revocation 

(D) Relocation

Ans: (B)


Q.23 ________ is the time required by a sector to reach below read/write head.

(A) Seek Time 

(B) Latency Time

(C) Access time 

(D) None

Ans: (B)


Q.24 Which of the following is most general phase structured grammar?

(A) Context – Sensitive 

(B) Regular

(C) Context – Free 

(D) None of the above

Ans: (A)


Q.25 File record length

(A) Should always be fixed

(B) Should always be variable

(C) Depends upon the size of file

(D) Should be chosen to match the data characteristics.

Ans: (D)


Q.26 A public key encryption system

(A) Allows only the correct receiver to decode the data

(B) Allows only one to decode the transmission.

(C) Allows only the correct sender to decode the data.

(D) Does not encode the data before transmitting it.

Ans: (A)

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