UGC NET Paper 2 Computer Science Mock Test - 2 - UGC NET MCQ

The following scheduling algorithms may cause starvation:

• First-come-first-served- No starvation
• Round Robin-  No starvation
• Priority- starvation if higher priority process called again and again, lower priority starves
• Shortest process next -starvation possible
• Shortest remaining time first -starvation possible as its a preemptive version of shortest process next casuing apotential for longer processes to starve.

Answer must be B

• The simple description of the problem:
• Five silent philosophers sit at a round table with bowls of spaghetti.Forks are placed between each pair of adjacent philosophers.
• Each philosopher must alternately think and eat.
• However, a philosopher can only eat spaghetti when he has both left and right forks.
• Each fork can be held by only one philosopher and so a philosopher can use the fork only if it is not being used by another philosopher.
• After he finishes eating, he needs to put down both forks so they become available to others.
• A philosopher can take the fork on his right or the one on his left as they become available, but cannot start eating before getting both of them.
• Eating is not limited by the remaining amounts of spaghetti or stomach space; an infinite supply and an infinite demand are assumed.
• The problem is how to design a discipline of behavior (a concurrent algorithm) such that no philosopher will starve; i.e., each can forever continue to alternate between eating and thinking, assuming that no philosopher can know when others may want to eat or think.

Both S1 and S2 are correct statements about compilers.

S1: It is a system software to convert source language program into target language program.

1. A compiler is a system software that is used to convert source code written in a high-level programming language like C, C++, Java, Python, etc., into machine language (binary code) that can be executed by the computer's hardware.
2. The compiler translates the source code into an intermediate form (assembly code), and then into machine language, which can be understood by the computer's CPU.
3. The process of translating high-level code into machine language is called compilation.

S2: It validates the input program to the source language specification – produces error messages /warnings.

1. When a program is written in a programming language, it has to confirm to a specific set of rules and syntax.
2. The compiler validates the input program to the source language specification and produces error messages and warnings if the program violates any of the rules or syntax.
3. For example, if a program tries to use an undefined variable, the compiler will produce an error message indicating that the variable is undefined.
4. Similarly, if the program contains syntax errors like missing semicolons or parentheses, the compiler will generate error messages and prevent the program from being compiled.

let's take an example to understand the role of a compiler in converting source code into machine code and detecting errors.

Suppose we have the following C program:

#include <stdio.h>

int main() {
printf("Hello, World!");
return 0;
}

This program is written in C language and is intended to display the text "Hello, World!" on the screen when executed.

When we run this program, the compiler will perform the following steps:

• The preprocessor will include the header file stdio.h, which contains the standard input/output library functions.
• The compiler will analyze the syntax of the program to ensure that it conforms to the rules and syntax of the C language.
• If there are any syntax errors, the compiler will produce an error message and stop the compilation process.

For example, if we misspelled printf as print, the compiler would produce the following error message:

error: implicit declaration of function ‘print’

• If there are no syntax errors, the compiler will translate the C code into an intermediate language called assembly language. This process is called assembly.
• Finally, the assembler will convert the assembly code into machine code, which can be executed by the computer's hardware. This process is called linking.

If there are any errors or warnings detected during any of these steps, the compiler will report them to the programmer.

For example, if we forgot to include the stdio.h header file, the compiler would produce the following warning message:

warning: implicit declaration of function ‘printf’

• By reporting errors and warnings,
• the compiler helps the programmer to identify and fix problems in their code,
• making the process of developing software more efficient and reliable.

The correct answer is option 4.

Concept:

​Plagiarism:

Plagiarism is when you promote someone else's work or ideas as your own, with or without their permission, by combining them into your work without giving them full acknowledgment.

If we copy some content from the Internet but do not mention the source or the original creator, then it is considered an act of plagiarism.

Hence the correct answer is Plagiarism.

Additional Information

• Hacking is the act of unauthorized access to a computer, computer network, or any digital system. Hackers usually have the technical expertise in hardware and software.
• Identity thieves increasingly use personal information stolen from computers or computer networks, to commit fraud by using the data gained unlawfully.
• Cyberbullying is bullying with the use of digital technologies. It can take place on social media, messaging platforms, gaming platforms, and mobile phones.

The correct answer is option 3.

Concept:

Option i: There exists a recursively enumerable language whose complement is not recursively enumerable.

True, Recursive enumerable languages are not closed under complementation. Recursive enumerable is may or may not be closed with respect to string.

Hence there exists a recursively enumerable language whose complement is not recursively enumerable.

option ii: If a language L is recursive, then its complement is NOT recursive.

False, The complement of a recursive language is recursive. If a language L and its complement are Recursive, then L is recursive. Hence If a language L is recursive, then its complement is NOT recursive.

Hence the correct answer is Only (ii).

Additional Information

The correct answer is option 1.

Key Points

Apply first cross-product then apply filter. Cross product yields 10 rows, then you play filter A.ID>40 or C.ID<15 produces 7 rows.

AUB= A.Id

12,15,25,98,99

|x| is cross product followed selection and projection.

Hence the correct answer is 7.

Only tables for entity sets A and B are needed. As the participation of A in the relationship is total we can combine the table A and R to form a single table. Two tables formed are as

A: {A1, A2, B1}

0 3 4 8 10 15

Completion time of P2 is 15.

Processes:

• P1: AT = 0.000, ST = 3

• P2: AT = 1.001, ST = 6

• P3: AT = 4.001, ST = 4

• P4: AT = 6.001, ST = 2

Step 1: Start with P1

• At time 0.000 → only P1 is available.

• P1 runs from 0.000 to 3.000 (completes, since no interruption).

Step 2: Process P2 enters

• At 1.001, P2 arrives (but P1 is still running and shorter, so no preemption).

• At 3.000, P1 finishes.

• Now ready queue: P2 (6).

• P2 starts at 3.000.

Step 3: Process P3 arrives

• At 4.001, P3 arrives (service time = 4).

• At this time, P2 has already run 1 unit (from 3.000 to 4.001). Remaining time of P2 = 5.

• Compare P2 (remaining 5) vs P3 (4). → P3 is shorter, so preempt P2.

• P3 starts at 4.001.

Step 4: Process P4 arrives

• At 6.001, P4 arrives (service time = 2).

• At that moment, P3 has already run for 2 units (from 4.001 to 6.001). Remaining time of P3 = 2.

• Compare: P3 (remaining 2) vs P2 (5) vs P4 (2).

• Tie between P3 (2) and P4 (2). Since P3 is already running, it continues.

Step 5: Completion of P3

• P3 runs from 6.001 to 8.001 → completes.

Step 6: Calculate Waiting Time of P3

• Arrival Time (AT) = 4.001

• Start Time (first execution) = 4.001

• Waiting time = (Start time – Arrival time) + (time spent waiting in between, if preempted).

• Here, P3 started immediately at arrival (4.001) and was never preempted before completion.

So, Waiting Time of P3 = 0.

Final Answer:

d) 0

The correct answer is option 1.

Concept:

The interrupt is a signal emitted by hardware or software when a process or an event needs immediate attention. It alerts the processor to a high-priority process requiring interruption of the current working process.

Option 1: If a process is interrupted during system call handling then the OS will crash.

False, If a process is interrupted during a system call then the system call was interrupted and the system call returned an error so definitely OS will not crash.

Option 2: If a process is interrupted during system call handling then the process is moved to the READY queue.

False, When a process is interrupted, that process is transferred to the waiting queue. If the process has been completed or aborted, the process is discarded. In either case, the dispatcher then selects a process from the queue to execute.

Option 3: If an interrupt handler is interrupted, the OS will crash.

False, If an interrupt handler is interrupted, such kernel control paths may be arbitrarily nested an interrupt handler may be interrupted by another interrupt handler, thus giving rise to a nested execution of kernel threads.

Hence the correct answer is none of the above.

Adelson-Velskii and Landis (AVL) tree is a height-balanced binary search tree. An AVL tree is a balanced binary search tree. In an AVL tree, the balance factor of every node is either -1, 0, or +1. The balance factor of a node is the difference between the heights of the left and right subtrees of that node.

So at every node of the AVL tree must satisfy the |h(TL) - h(TR)| ≤ 1.

Hence the correct answer is |h(TL) - h(TR)| ≤ 1.

Here 20 is less than 38.

So we go to left side than 14 is less than 20 than we go to right side of 14.

Here we place the 20 than check whether tree is balanced.

Now, check tree is balance here 23 is unbalanced so rotating in right shift.

we get,

I) True

Zero in sign magnitude form:

Zero in 1’s magnitude form:

Zero in 2’s magnitude form:

ii) True: In sign magnitude form addition and subtraction is performed on separate hardware.

iii) True: For k-bits, range in 2’s compliment number is:

-2^k-1 to 2^k-1-1

∴ for 3 bits

its -4 to +3

Instruction size = 2 byte = 16 bits

Addressing mode = 1 bit

operand = 1 byte = 8 bits

Instruction size = Addressing mode + opcode + operand

16 = 1 + opcode + 8

∴ opcode = 7 bits

Instruction code format:

The correct answer is Pixel.

Key Points

• Pixel stands for "Picture Element."
• Pixel is also known as "PEL."
• Pixel is the smallest element of an image on a computer display.
• It includes both types of display that is LCD or CRT monitors.
• A screen is made up of a matrix of thousands or millions of pixels.
• It is represented with a dot or a square on a computer screen.
• Each pixel has a unique logical address.
• It can have a single color at a time.
• The Colour of a pixel is determined by the number of bits which is used to represent it.
• A resolution of a computer screen depends upon the graphics card and display monitor, the quantity, size and color combination of pixels.
• When an image has zoomed in, the surface of the image will look like filled dots and these dots are light receptors called photodiode.
• These dots are known as pixels.

Given:

The edges of the polyhedron = 30

The faces of the polyhedron = 12

Formula used:

Euler's formula for the polyhedron

F + V = E + 2 (Where F = The face of the polyhedron, V = The vertices of the polyhedron, and E = The edge of the polyhedron)

Calculation:

Let be assume the vertices of the polyhedron is V

⇒ 12 + V = 30 + 2

⇒ V = 32 - 12 = 20

∴ The required result will be 20.

• During DMA the CPU is idle and it has no control over the memory buses. The DMA controller takes over the buses to manage the transfer directly between the I/O devices and the memory unit.
• Bus Request: It is used by the DMA controller to request the CPU to relinquish the control of the buses.
• Bus Grant: It is activated by the CPU to inform the external DMA controller that the buses are in high impedance state and the requesting DMA can take control of the buses.
• After the completion of the DMA transfer, the processor is notified by an interrupt signal.
• The Controller uses the registers to store the starting address, word count and the status of the operation.

The correct answer is Nonlinear functions

Key Points

• Neural networks are complex nonlinear functions with many parameters, and this nonlinearity is crucial to their success. Here's a more detailed explanation:
• Neural networks are essentially systems of neurons, or nodes, organized into layers. Each node in a given layer receives inputs from nodes in the previous layer, multiplies these inputs by specific weights (the parameters of the neural network), adds a bias term, and then applies a nonlinear function to the result. This is known as the activation function.
• Activation functions are what introduce nonlinearity into the network. They help neural networks learn from error gradients during the training process, and the nonlinearity allows them to model complex patterns and datasets that simple linear regression would not be able to. An example of a common nonlinear activation function is the Rectified Linear Unit, or ReLU, which outputs the input directly if it is positive, else it will output zero.
• The network as a whole, possessing layers of these nonlinear nodes generating outputs based on their inputs, can be said to represent a complex, high-dimensional, nonlinear function that maps input data to output data. The many parameters of the network (the weights and biases at each node) are learned through an iterative process in which the network adjusts these parameters to reduce the difference between its actual outputs and the outputs it should have produced (the "ground truth").
• This nonlinear quality allows neural networks to model complex phenomena, capture interactions between variables, fit themselves to diverse sets of data, and make predictions or classifications with high accuracy. Linear models are usually less flexible and less capable of modelling complex datasets than nonlinear ones like neural networks.
• That's why it's best to consider neural networks as complex nonlinear functions with many parameters.

Simplex method: It is a step by step method in which solution is started with initial feasible solution and in the next step the initial feasible solution is improved, the steps are repeated until the optimum solution is reached.

Following are the set of variables in Simplex Method.

• Artificial Variable
  • This variable is introduced in case of greater than or equal to type constraint to not violate the non-negativity constraint.
• Basic Variables
  • They can be defined as the variables which can take any value other than zero.
• Non basic Variables
  • This variable is not in the basic solution and is having the value zero.
• Slack Variable
  • This variable is introduced in the simplex method to eliminate less-than (<) constraints.
• Surplus Variable
  • This variable is introduced in the simplex method to eliminate greater-than (>) constraints.

A simplex table is shown below for example for the given objective function and constraints

Maximize Z = 4 x1 + 6 x2 + x3

Subject to 2 x1 - x2 + 3 x3 ≤ 5

x₂ ≤ 2

x₁, x₂, x₃ ≥ 0

Following are the special cases of simplex method:

Under Simplex Method, the existence of multiple optimal solutions is indicated by a situation under which a non-basic variable in the final simplex table showing optimal solution to a problem, has a net zero contribution.

Optimal solution: If at least one of the non-basic variable in the (Cj- Zj) row of the final simplex table has a zero value, it indicates that there is more than one optimal solution.

Unbounded solution: If all the replacement rations, bi/ai (ai – key column or pivot column coefficient are negative) then it is the solution is unbounded.

Infeasible solution: If artificial variables are present in the base, then the solution obtained is infeasible.

Degenerate solution: If some of the values in the constant column (bi) are zero, then the solution becomes degenerate.

The correct answer is option 3.

Concept:

Distributed DBMS:

A distributed database is a set of interconnected databases that are distributed over the computer network or internet.

Centralized DBMS:

A centralized database is stored at a single location such as a mainframe computer.

S1: In a distributed DBMS, databases are stored at many locations with the use of a network, as compared to a centralized DBMS, which stores databases at a single location.

True, In Centralized DBMS the database is stored on only one site. In Distributed DBMS the database is stored on different sites and the help of the network can access it.

S2: When a centralized system fails, the entire system is brought to a halt, whereas in a distributed DBMS, If one system fails, the system keeps working with the other site.

True, If the centralized system fails, the entire system is halted. In Distributed DBMS If one system fails, the system continues to work with another site.

Hence the correct answer is Both S1 and S2.

• Compile time: If memory location known a priori, absolute code can be generated; must recompile code if starting location changes.
• Load time: Must generate relocatable code if memory location is not known at compile time.
• The execution time or CPU time of a given task is defined as the time spent by the system executing that task, including the time spent executing run-time or system services on its behalf.

The Expression Builder is a general-purpose tool that helps you construct WEAP's expressions by dragging and dropping the functions and WEAP Branches into an editing box.

The interval from the time of submission of a process to the time of completion is the turnaround time. It can also be considered as the sum of the time periods spent waiting to get into memory or ready queue, execution on CPU and executing input/output. Turnaround time is an important metric in evaluating the scheduling algorithms of an operating system.

Multiple repeaters in communication satellites are called transponders. A radio or radar set that upon receiving a designated signal emits a radio signal of its own and that is used especially for the detection, identification, and location of objects and in satellites for relaying communications signals. A communications satellite's channels are called transponders because each is a separate transceiver or repeater.

The advantage of dynamic loading is that an unused routine is never loaded. Dynamic loading does not require special support from the OS. Operating systems may help the programmer, however, by providing library routines to implement dynamic loading.

The main intent of project metrics is to minimize the development schedule and evaluate the ongoing project's quality on a daily basis. A project metric refers to a quantifiable measure of the degree to which a system, component, or process owns a certain trait. A metric is simply a measurement of something. When managing a project, you can choose to use project metrics to track progress. Metrics are selected based on the goals of the project and critical factors for success.