U.G.C. NET Exam. June, 2020 Paper II (COMPUTER SCIENCE & APPLICATIONS)

Total Questions: 100

91. If T is capacity of a track is bytes, and S is the capacity of each surface in bytes then, (T.S) = ____ .

Correct Answer: (c) (25 K, 50000 K)
Solution:

Track capacity = bytes/sector X sector/track = 512×50 = 25 K bytes/track
Surface capacity = bytes/track×track surface = 25k×2000 = 50000 (bytes/...)

92. What is the capacity of the disk, in bytes?

Correct Answer: (b) 5000000 K
Solution:

Capacity of the disk = bytes/sector x Sector/truck ×track / surface× surface/disk. =
512×50 ×2000×5×2 = 5000000 K

93. Given below are tow statements :

Statement I : The disk has a total number of 2000 cylinders.
Statement II: 51200 bytes in not a valid black size for the disk.
In the light of the above statements, choose the correct answer from the options given below.

Correct Answer: (a) Both statement I and statement II are true
Solution:

Statement-I The number of cylinder is 2000, which is the same or the number of tracks on each platter.
Statement-II The block size will be a multiple of the sector size. 51200 is not a valid block size in this case because block size cannot exceed the size of a track, which is 25600 bytes.

94. If the disk platters rotate at 5400 rpm (revolutions per minute), then approximately what is the maximum rotational delay?

Correct Answer: (a) 0.011 seconds
Solution:In the disk platters rotate at 5400 rpm.

95. If one track of data can be transferred per revolution, then what is the data transfer rate ?

Correct Answer: (d) 2250 KBytes/second
Solution:

96. On the basis of above given table structures, retrieve the distinct employee ID (EMPID) of all employee of university who are working in project No, 20, 30, and 40.

Correct Answer: (c) SELECT DISTINCT EMPID FROM PROJECT WORK, WHERE PROJNO IN (20, 30, 40);
Solution:

Since the primary key is a combination of two keys (EMPID, PROJNQ) so, duplicate values may occur in EMID and PROJNQ. So distinct key are required to eliminate duplicate in the combined table. AND IN is a set operator it matches all table values to the set values.
• SELECT DISTINCT EMPID FROM PROJECT work WHERE PROJNO IN (20, 30, 40).

97. Given below are two statement to find the sum of salaries of all employee of the English department as well as the maximum, minimum and average salary in English department.

STATEMENT I; SELCET SUM (SALARY), MAX (SALARY),, MIN (SALARY), AVG (SALARY) FROM EMPLOYEE, DERPARTMENT WHERE DECTNO = DID AND DNAME = 'ENGLISH'. STATEMENT II: SELCET SUM (SALARY), MAX (SALARY),, MIN (SALARY), AVG (SALARY) FROM EMPLOYEE, DERPARTMENT WHERE DNAME = 'ENGLISH'.
In the light of the above statements, choose the correct answer from the options given below.

Correct Answer: (c) Statement I is correct but statement II is false
Solution:

Two tables (join condition) must be matched so that records can be linked uniquely.
Query :- SUM (SALARY), MAX (SALARY), MIN (SALARY), AVG (SALARY) FROM EMPLOYEE, DERPARTMENT WHERE DEPTNO = DID AND DNAME = 'ENGLISH'
Without DEPTNO = DID condition as in statement II, there will be the Cartesian product of two tables (EMPLOYEE, DEPARTMENT) and it will appear many duplicate row with
DNAME = 'ENGLISH'
Hence statement I is correct but statement II is false.

98. Which of the following query/queries return the employee ID and name of employee whose salary is greater than the salary of all employee in department number 20 of university. Order result by employee ID (refer table structure given above).

(A) SELECT EID. NAME FROM EMPLOYEE WHERE SALARY > (SELECT SALARY FROM EMPLOYEE WHERE DEPTNO = 20); ORDER BY EID
(B) SELECT EDI NAME FROM EMPLOYEE WHERE SALARY > (SELECT SALARY FROM EMPLOYEE WHERE DEPTNO = 20);
(C) SELECT EID, NAME FROM EMPLOYEE WHERE SALARY > ALL(SELECT FROM EMPLOYEE WHERE DEPTNO = 20) ORDER BY EID
Choose the correct answer from the options given below:

Correct Answer: (d) (C) only
Solution:

SELECT SALARY FROM EMPLOYEE WHERE DEPTNO = 20 The above inner query will be written the salary is of an employee whose department number is 20 this will match with the salary of the employee > salary of at least one employee.
Query :- SELECT EID, NAME
FROM EMPLOYEE
WHERE SALARY>ALL(SELECT FROM EMPLOYEE WHERE DEPTNO = 20)                            ORDER BY EID
The query returns the employee ID and name of employees whose salary is grater then the salary of all employees in department number 20 of the university or order result by employee ID.

99. In reference to the above given table structure, which of the following query/queries will drop the 'SALARY' column from 'ENPLOYEE' table?

(A) ABTER TABLE EMPLYOEE DROP SALARY CASCASE.
(B) ALTER TABLE EMPLOYEE DROP SALARY RESTRUCT.
(C) ALTER EMPLOYEE DROP SALARY.
Choose the correct answer from the options given below:

Correct Answer: (a) (A) and (B) only
Solution:

Alter table syntax:- ALTER TABLE table-name DROP [COLUMN] column-name [CASCADE | RESTRICT]
• The key word COLUMN, CASCADE, RESTRICT are optional. The default CASCADE. It you use the RESTRICT option, the column drop will be rejected if it would invalidate a dependent, schema object. •
Since the salary field is not present in any other table CASCADE |RESTRICT| has no impact.
• (c) ALTER ECMPLOYEE DROP SALARY is incorrect syntax.
Hence the correct answer is (a) and (b) only.

100. Refer table structures given above University decided to give all employee in the 'SCIENCE' department a 20% rise in salary. Which of the following query/queries will compute the above results?

(A) UPDATE EMPLOYEE SET SALARY = SALARY*1.20 WHERE DEPT NO. IN (SELECT DID FROM DEPARTMENT WHERE DNAME = SCIENCE);
(B) UPDATE TABLE EMPLOYEE SET SALARY = SALARY*1.20 WHERE DBAME = SCIENCE;
(C) ALTER TABLE EMPLOYEE SET SALARAY = SALARY*1.20 WHERE DETINO, IN (SELECT DNAME FROM DEPRTMENT WHERE DNAME = 'SCICENCE')
Choose the correct answer from the options given below: 

Correct Answer: (b) (A) only
Solution:

Syntax :- UPDATE table _ name SET column 1 = value 1, column 2 = value 2, ..... WHERE condition.
(A) UPDATE EMPLOYEE
SET SALARY = SALARY*1.20
WHERE DEPT NO. IN (SELECT DID
FROM DEPARTMENT WHERE DNAME =
"SCIENCE");