CS GATE 2012 - Online Test
Q1. Which of the following is TRUE?
Answer : Option C
Explaination / Solution:
Option A is false since BCNF is stricter than 3NF (it needs LHS of all FDs should be candidate
key for 3NF condition)
Option B is false since the definition given here is of 2NF
Option C is true, since for a relation to be in BCNF it needs to be in 3NF, every relation in
BCNF satisfies all the properties of 3NF.
Option D is false, since if a relation is in BCNF it will always be in 3NF.
Q2. What is the minimal form of the Karnaugh map shown below? Assume that X denotes a don’t
care term.
Answer : Option B
Explaination / Solution:
Q3. Consider the following C code segment:
int a, b, c = 0;
void prtFun(void);
main( )
{ static int a = 1; /* Line 1 */
prtFun( );
a + = 1;
prtFun( )
printf(“\n %d %d “, a, b);
}
void prtFun(void)
{ static int a=2; /* Line 2 */
int b=1;
a+=++b;
printf(“\n %d %d “, a, b);
}
What output will be generated by the given code segment?
Answer : Option C
Explaination / Solution:
Q4. Suppose R1 
are two relation schemas. Let r1 and r2 be the
corresponding relation instances. B is a foreign key that refers to C in R2. If data in r1 and r2 satisfy referential integrity constrains, which of the following is ALWAYS TRUE?
are two relation schemas. Let r1 and r2 be the
corresponding relation instances. B is a foreign key that refers to C in R2. If data in r1 and r2 satisfy referential integrity constrains, which of the following is ALWAYS TRUE?
Answer : Option A
Explaination / Solution:
No Explaination.
Q5. Which of the following problems are decidable?
1) Does a given program ever produce an output?
2) If L is context-free language, then, is 
also context-free?
also context-free? 3) If L is regular language, then, is 
also regular?
also regular? 4) If L is recursive language, then, is 
also recursive?
also recursive?
Answer : Option D
Explaination / Solution:
CFL’s are not closed under complementation. Regular and recursive languages are closed
under complementation.
Q6. The amount of ROM needed to implement a 4 bit multiplier is
Answer : Option D
Explaination / Solution:
For a 4 bit multiplier there are 24 × 24 = 28 = 256 combinations.
Output will contain 8 bits.
So the amount of ROM needed is 28 ×8 bits = 2Kbits
Q7. Consider the following relations A, B and C:
How many tuples does the result of the following SQL query contain?
SELECT A.Id
FROM A
WHERE A.Age > ALL(SELECT B.Age FROM B
WHERE B.Name = ‘Arun’)
Answer : Option B
Explaination / Solution:
As the result of subquery is an empty table, ‘>ALL’ comparison is true . Therefore, all the
three row id’s of A will be selected from table A.
Q8. Given the language L-{ab, aa, baa}, which of the following strings are in L*?
1) abaabaaabaa
2) aaaabaaaa
3) baaaaabaaaab
4) baaaaabaa
Answer : Option C
Explaination / Solution:
L ={ab, aa, baa}
Let S1 = ab , S2 = aa and S3 =baa
abaabaaabaa can be written as S1S2S3S1S2
aaaabaaaa can be written as S1S1S3S1
baaaaabaa can be written as S3S2S1S2
Q9. A process executes the code
fork ();
fork ();
fork ();
The total number of child processes created is
Answer : Option C
Explaination / Solution:
If fork is called n times, there will be total 2n running processes including the parent process.
So, there will be 2n -1 child processes.
Q10. Consider the following relations A, B and C:
How many tuples does the result of the following relational algebra expression contain?
Assume that the schema of A ∪ B is the same as that of A.
Answer : Option A
Explaination / Solution:
