PREVIOUS YEAR SOLVED PAPERS MCQ - GATE 2020

21 Which one of the following is used to represent the supporting many-one relationships of a weak entity set in an entity-relationship diagram?

22 Consider a relational database containing the following schemas.

The primary key of each table is indicated by underlining the constituent fields
SELECT s.sno, s.sname
FROM Suppliers s, Catalogue c
WHERE s.sno = c.sno AND
Cost > (SELECT AVG (cost)
FROM Catalogue
WHERE pno = ‘P4’
GROUP BY pno);
The number of rows returned by the above SQL query is

Therefore 4 rows returned by the above query.

23 Consider the following statements about the functionality of an IP based router.
I. A router does not modify the packets during forwarding.
II. It is not necessary for a router to implement any routing protocol.
III. A router should reassemble IP fragments if the MTU of the outing packet is larger than the size of the incoming IP packet.
Which of the above statements is/are TRUE?

Statement 1: False, Because, Intermediate router may modify fields like TTL, offset checksum.
Statement 2: True, router may not implement routing protocol, for static routing.
Statement 3: False, It is not mandatory to reassemble.

24 Consider allocation of memory to a new process. Assume that none of the existing holes in the memory will exactly fit the process’s memory requirement. Hence, a new hole of smaller size will be created if allocation is made of the existing holes. Which one of the following statements is TRUE?

Let us consider a new process required 120 kb memory and existing holes in the memory are 200, 300, 150 kb as shown in the diagram in the same order.

Now, when we allocate, this new process a memory using different algorithms, it would be like given below
Algorithm Allocated partition size of new tube
First Fit 200 KB 80 KB
Best Fit 150 KB 30 KB
Worst Fit 300 KB 180 KB
Next Fit 300 KB 180 KB

25 Consider the following sentences.
I. If L₁ ⋃ L₂ is regular, then both L₁ and L₂ must be regular.
II. The class of regular languages is closed under infinite union.
Which of the above statements is/are TRUE?

Let L₁ = an bn⇒ CFL
L₂ = Σ* ⇒ Regular
L₁ ∪ L₂ = (aⁿ bⁿ) ∪ Σ* = Σ* ⇒ Regular
Since L₁ ∪ L₂ is regular but L₁ is not regular, Hence statement I is false.
Regular language is not closed under infinite union.
Hence, statement-II is also false.
∴ Neither I nor II is true.

i = 0	i = 1	i = 2
ex = 3 x 3	ex = 9 x 3	tot = t * t *ex
= 9	= 81	= 1 * 81 = 81