RRB JE IT CBT 2 Full Test 1 - Railways MCQ

JVM (Java Virtual Machine) is an abstract machine. It is a specification that provides runtime environment in which java bytecode can be executed. JVM does not create the object of main class. Java is platform independent but JVM is platform dependent. JVM is the one that actually calls the main method present in a java code.

Linux Operating System has primarily three components:
1. Kernel
2. System libraries
3. System utilities

Kernel: The kernel is responsible for maintaining all the important abstractions of the operating system, including such things as virtual memory and processes.

System libraries: The system libraries define a standard set of functions through which applications can interact with the kernel. These functions implement much of the operating-system functionality that does not need the full privileges of kernel code.

System utilities: The system utilities are programs that perform individual, specialized management tasks.

A bus that connects major computer components (processor, memory, I/O) is called a system bus.

Any bus the lines can be classified into three functional groups: data, address, and control lines.

The data lines provide a path for moving data among system modules. These lines, collectively, are called the data bus.

The address lines are used to designate the source or destination of the data on the data bus.

The control lines are used to control the access to and the use of the data and address lines. Because the data and address lines are shared by all components, there must be a means of controlling their use.

File infector virus is also known as a parasitic virus that usually infects memory and executable files.

A boot sector virus is a type of virus that infects the boot sector of floppy disks or the Master Boot Record (MBR) of hard disks.

A macro virus is a computer virus written in the same macro language used for software programs, including Microsoft Excel or word processors such as Microsoft Word.

A cursor is used to iterate through a result set that was returned by a SELECT statement. Cursors can be used in stored procedures, stored functions, and triggers.

A hit is the term used when a search engine return a Web page that matches the search criteria. Blog is the place where any article is written and published over internet. Link opens up new website.

• Krishna Sobti was a famous Hindi writer and essayist.
• She had won the Sahitya Akademi Award in 1980 for her novel Zindaginama.
• She was awarded the Jnanpith in 2017 for her contribution to Indian literature.
• Some of her celebrated works include Daar Se Bichhudi, Mitro Marjani, Zindaginama, Dil-o-Danish etc.

Direct memory access (DMA) is a method that allows an input/output (I/O) device to send or receive data directly to or from the main memory, bypassing the CPU to speed up memory operations. The process is managed by a chip known as a DMA controller (DMAC).

In the Internet protocol stack, when data is sent from device A to device B, the 5th layer to receive data at B is Application layer. The application layer is a layer in the Open Systems Interconnection (OSI) seven-layer model and in the TCP/IP protocol suite. It consists of protocols that focus on process-to-process communication across an IP network and provides a firm communication interface and end-user services. Example: HTTP, TELNET, FTP, IMAP etc.

A function provides a convenient way to encapsulate some computation. C makes the use of functions easy, convenient and efficient.

Functions receive either a fixed or variable amount of arguments. Functions can only return one value or return no value. A function returns all mentioned data-types,

man stands for manual.
The man pages are a user manual that is by default built into most Linux distributions.
man command in Linux is used to display the user manual of any command.

Fifth Generation (Present and Future):

• 5th generation computers use ULSI (Ultra-Large Scale Integration) chips
• Millions of transistors are placed in a single IC in ULSI chips
• 64-bit microprocessors have been developed during this period
• Memory chips and flash memory up to 1 GB, hard disks up to 600 GB & optical disks up to 50 GB have been developed
• Fifth generation computing devices, based on Artificial Intelligence, are still in development, though there are some applications, such as voice recognition, that is being used today

Notes:

The cd command, also known as chdir (change directory), is a command-line OS shell command used to change the current working directory in operating systems.

if the user wanted to change from the home directory to the xyz directory, the input will be:

cd/xyz/

Octal number system has 8 digits from 0…. 7
Hence 8 cannot be a symbol in the octal number system
Hence option d 678 is incorrect

A queue is an ordered list in which insertions are done at one end (rear) and deletions are done at another end (front). The first element to be inserted is the first one to be deleted. Hence, it is called First in First out (FIFO) or Last in Last out (LILO) list.

Condition for size of queue: rear = maximum_size – 1

<tr> tag is used to add rows in tables
The <tr> tag defines a row in an HTML table
A <tr> element contains one or more <th> or <td> elements
The <th> tag defines a header cell in an HTML table
The <td> tag defines a standard cell in an HTML table

A method must be declared within a class. It is defined with the name of the method, followed by parentheses ().

JAVA (static) method can be accessed without creating an object of the class or it can be accessed by creating objects using the corresponding class.

A constructor in Java is a special method that is used to initialize objects. Java constructor is invoked at the time of object creation. It constructs the values for the object that is why it is known as constructor.

The Battle of Buxarwas fought on 22-23 October 1764 between the forces under the command of the British East India Company led by Hector Munro and the combined armies of Mir Qasim, Nawab of Bengal till 1763; the Nawab of Awadh; and the Mughal Emperor Shah Alam.

• The combined armies of Mughals, Awadh and MirQasim were defeated by the British army.
• Treaty of Allahabad was signed after the battle of Buxar.

Requirements validation examines the specification to ensure that all system requirements have been stated unambiguously; that inconsistencies, omissions, and errors have been detected and corrected; and that the work products conform to the standards established for the process, the project, and the product.

Binary search is also known as half-interval search. It works efficiently with a sorted list. Binary search compares the target value to the middle element of the list. If they are not equal narrow the interval to the lower half (i.e. elements appear before middle element). Otherwise, narrow it to the upper half (i.e. element appear after middle element). Repeatedly check until the target value is found.

Pre-requisite for binary search is to have a sorted array.

The home page is the first page that we see when a website is opened on the web browser. It is also called the start page or the main page, though home page is a more commonly used name. It is generally made attractive and contains various hyperlinks to different pages within the web site to attract visitors to its site. Some web sites require users to login to the web site to access the home page.

System software is a type of computer program that is designed to run a computer's hardware and application programs. If we think of the computer system as a layered model, the system software is the interface between the hardware and user applications.

x=-x-1 will give negative result.
x=-+x is invalid use of operator.
x = -x- - will provide negative output.
x+=-1 is equivalent to x = x+(-1), hence x = x -1.

• The Centripetal force is required to maintain a body in Uniform Circular Motion.
• Centripetal Force acts when a body moves around the other body, the force that causes this acceleration and keeps the body moving along a circular path is acting towards the centre

Java is a general-purpose computer programming language that is concurrent, class-based, object-oriented, and specifically designed to have as few implementation dependencies as possible.

Java constructor is invoked at the time of object creation. It constructs the values for the object that is why it is known as constructor.

JAVA is intended to let application developers "write once, run anywhere" (WORA), meaning that compiled Java code can run on all platforms that support Java without the need for recompilation.

The <img> tag defines an image in an HTML page.

The <img> tag has two required attributes: src and alt.

src specifies the URL of an image and alt specifies an alternate text for an image.

• Methane and Carbon dioxide are the main constituent of Biogas.
• Methane is produced by the anaerobic bacterial decomposition of vegetable matter under water.
• It is also known as marsh gas or swamp gas.
• Its chemical formula is CH_4.

• Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air.
• These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.
• Sulfur dioxide and nitrogen oxides dissolve very easily in water and can be carried very far by the wind.
• As a result, the two compounds can travel long distances where they become part of the rain, sleet, snow, and fog that we experience on certain days.

• In γ-emission rays (Gamma rays), no changes occur in the mass/charge.
• Gamma rays are electromagnetic waves of short wavelength and high frequency.
• They are emitted by most radioactive sources along with alpha or beta particles
• Through releasing a gamma photon it reduces to a lower energy state. Hence, Gamma rays have no electrical charge connected with them.
• Alpha rays are released by high mass whereas beta has high energy electrons.

Logical operators are used to combine and evaluate boolean expressions.

&& called Logical AND operator. If both the operands are non-zero, then the condition becomes true.

|| called Logical OR Operator. If any of the two operands is non-zero, then the condition becomes true.