Bihar STET Paper 2 Computer Science (Class 11-12) PYQ, 12 Sep 2023, Shift 2

Explanation

Codes in which adjacent values differ in only one bit are Gray codes; this unit-distance property is what the question describes. (Strictly, the classic self-complementing code is Excess-3, but the one-bit-change description fits only Gray code.)

Explanation

A decimal digit 0-9 needs 4 bits (2⁴ = 16 ≥ 10), so a decimal digit in Gray code (like BCD) uses 4 bits.

Explanation

The options only list minterms rather than a true minimal form; grouping on the K-map actually gives F = A'C' + BC' + A'D' + B'CD'. The key gives (B) as the closest listed expression.

Explanation

A binary-to-Gray converter translates one code into another, so it is a code converter, which is classed with encoders; it is built from XOR gates, not a decoder, comparator or multiplexer.

Explanation

PLDs (PROM, PAL, PLA, FPGA) contain programmable AND/OR arrays and I/O so the user can implement custom logic; many are reprogrammable and they are not just memory.

Explanation

Microcontrollers are cheap embedded chips used in home automation for tasks like reading sensors and controlling temperature, lights and appliances; the other options need large specialised systems.

Explanation

Harvard architecture uses separate memories and buses for program instructions and data, so both can be fetched at the same time; von Neumann uses one shared memory.

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Don't-care cells are those whose output does not matter; they need not be covered and may be taken as 1 only when this gives larger groups. (Strictly, option B, an undefined output value, describes them more accurately.)

Explanation

Each hex digit maps to 4 bits: F = 1111 and 4 = 0100, so F4 = 11110100.

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The clock/oscillator generates regular timing pulses that synchronise the fetch-execute steps and all data transfers in the microcomputer.

Explanation

Binary search halves the search range on every comparison, so at most about log₂n + 1 comparisons are needed: O(log n).

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A spanning tree on n vertices is a tree, and every tree with n vertices has exactly n - 1 edges, so the minimum (and only) count is n - 1.

Explanation

Optimal BST uses dynamic programming because an optimal tree's left and right subtrees must themselves be optimal (optimal substructure), with overlapping subproblems reused from a table.

Explanation

Floyd-Warshall runs three nested loops over k, i and j, each from 1 to n, so it takes O(n³) time.

Explanation

The divide-and-conquer MaxMin algorithm makes about 3n/2 - 2 comparisons; T(n) = 2T(n/2) + 2 solves to O(n).

Explanation

By the principle of optimality, a minimum-cost path through a multistage graph is built from minimum-cost sub-paths, so the shortest path is the one with the lowest total cost.

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Integer is a primitive (built-in) data type, while stack, queue and list are abstract data types defined by their operations, independent of implementation.

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A linked list is traversed linearly, following next pointers from head to the end, visiting each node once; preorder, inorder and postorder are tree traversals.

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Inserting at the beginning needs only to set newnode->next = head and head = newnode, which is O(1); inserting at the end or at a position requires traversal.

Explanation

Compressed sparse formats store only non-zero values with their indices; CSC compresses the data column by column, so it suits sparse matrices and column-wise access. CSR is the row-wise counterpart.

Explanation

CSR stores the non-zeros row by row with a row-pointer array, so all elements of a row are contiguous and can be traversed efficiently.

Explanation

An image is a grid of pixels addressed by row and column, so a 2-D array (one value per pixel, e.g. grayscale) is the natural structure.

Explanation

In row-major order the rows are stored one after another, so element (i, j) is at B + (i × n + j) for n columns (times the element size, taken as 1 here).

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The Banker's algorithm checks before each allocation whether the system stays in a safe state, so it avoids deadlock rather than detecting or preventing it.

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Monitors grew out of Dijkstra's ideas on structured synchronisation (his "secretary" concept) and were formalised by Brinch Hansen and Hoare; among the options only Dijkstra fits.

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Multilevel queue scheduling places processes in separate queues by priority class and serves higher-priority queues first, so it is built directly on priority scheduling.

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In deadlock detection, allocation and request matrices record which resources each process holds and requests, i.e. they represent resource allocation.

Explanation

A race condition occurs when processes access shared data concurrently and the result depends on the order of access, i.e. they compete for shared resources.

Explanation

Users' typed commands cannot be executed by the hardware as they are; the command interpreter (shell) reads each command and translates it into system calls and programs the machine can run.

Explanation

A multi-user OS (e.g. UNIX) lets several users use the same computer's resources at the same time, each with their own session.

Explanation

DML (SELECT, INSERT, UPDATE, DELETE) is used to query data and insert, modify and delete tuples; DDL defines structure, DCL controls permissions and TCL manages transactions.

Explanation

MySQL, Informix and SQL Server are all database management systems used to create and manage databases.

Explanation

One-to-many means one entity instance is linked to many instances of another, e.g. one teacher teaching many classes.

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A file is a collection of related records, and each record is made of related fields.

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A report generator takes data from files or databases and formats it into printed reports; it does not update files.

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A master file holds relatively permanent core data (e.g. customer or employee records) that is kept and updated over time, so it is called a perpetual file.

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Subnetting splits one network into smaller sub-networks, so a block of IP addresses is used efficiently instead of wasting a whole class.

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In upward multiplexing several transport connections are combined onto one network connection, i.e. multiple data streams share one channel; downward multiplexing does the reverse.

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Process-to-process delivery is the transport layer's job: port numbers identify the sending and receiving processes running on different hosts.

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HTTP is the application-layer protocol for transferring web pages between browsers and web servers, i.e. web browsing; email uses SMTP and file transfer FTP.

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HTTP stands for HyperText Transfer Protocol, the protocol for transferring web pages.

Explanation

An IPv6 address is 128 bits long (written as eight 16-bit hex groups), compared with 32 bits for IPv4.

Explanation

The IPv4 Total Length field is 16 bits, so a datagram can be at most 2¹⁶ - 1 = 65535 bytes, header included.

Explanation

Boehm's spiral model goes round repeated cycles of planning, risk analysis, prototyping and evaluation, so it is based on iterative prototyping.

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LOC means Lines of Code, a size metric used in effort estimation models such as COCOMO.

Explanation

The Delphi method asks several experts for anonymous estimates over repeated rounds until they reach consensus; COCOMO is an algorithmic model.

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ISO 9000 and SEI CMM are quality frameworks: ISO 9000 sets quality management standards, and CMM rates and improves the maturity of software processes.

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Perfective maintenance adds new features or improves performance in response to user needs; corrective fixes bugs and adaptive suits a new environment.

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ISO 9000 is a family of quality management standards that gives guidelines for producing software of consistent, high quality.

Explanation

Reverse engineering analyses existing software to recover and document its design, structure and functionality, often when documentation is missing.

Explanation

Overloading means several methods in the same class share a name but have different parameter lists; overriding redefines an inherited method with the same signature.

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Abstract classes can contain concrete methods with implementations plus fields and constructors, which (traditionally) interfaces could not.

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Namespaces group related classes and functions under a name, organising code logically and avoiding name clashes.

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Creating a new class from an existing one is derivation (inheritance); the new class is a derived class or subclass.

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An interface is a contract: it declares methods that every implementing class must define.

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An object is an instance of a class, and the variable that refers to that instance is an object reference, commonly just called the object.

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An exception is a runtime event (e.g. divide by zero) that disrupts the normal flow of instructions and can be caught and handled.

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A DTD defines the legal structure of an XML document: which elements and attributes are allowed, their order and nesting, so the document can be validated.

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PHP is a recursive acronym for "PHP: Hypertext Preprocessor" (originally "Personal Home Page").

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In PHP a single-line comment starts with // (or #); /* */ is a multi-line comment and <!-- --> is HTML.

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SELECT retrieves rows from tables; UPDATE, DELETE and INSERT modify data.

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CRUD stands for Create, Read, Update and Delete, the four basic operations on stored data (INSERT, SELECT, UPDATE, DELETE in SQL).

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DROP TABLE removes the table structure and its data from the database; DELETE removes only rows.

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A pushdown automaton (finite control plus a stack) accepts exactly the context-free languages; linear bounded automata accept context-sensitive languages.

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In the Chomsky hierarchy, Type 1 is context-sensitive; Type 0 is unrestricted, Type 2 is context-free and Type 3 is regular.

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In Chomsky normal form every production is A → BC (two variables) or A → a (a single terminal).

Explanation

Every rule adds one 0 and one 1 together (0S1, 1S0) or concatenates such strings (SS), so all generated strings have equal numbers of 0s and 1s.

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Recursively enumerable languages are Type 0 in the Chomsky hierarchy, generated by unrestricted grammars and recognised by Turing machines.

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A universal Turing machine takes the description of any other TM and its input and simulates it, so it is a reprogrammable (stored-program) Turing machine.

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A Turing machine can be described by a transition table, a transition diagram, or by instantaneous descriptions showing its configuration, so all of these apply.

Explanation

The common hobby RFID reader module (RC522, 13.56 MHz) has a short read range of about 5 cm.

Explanation

A ZigBee router relays and forwards data between devices in the network; the coordinator starts the network and end devices only send and receive their own data.

Explanation

Industry 4.0, the fourth industrial revolution, is defined by IoT, real-time data and cyber-physical systems in manufacturing.

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The Modbus serial line specification makes 19200 bps the required default baud rate for Modbus RTU devices (9600 is also commonly supported).

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iDisk was the online storage drive in Apple's MobileMe, where files could be browsed and shared; "iDesk" in the option refers to it.

Explanation

IoT resource management uses clustering, software agents and synchronisation techniques together, so all three listed approaches apply.

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A frame (Minsky) is a structure of slots and values describing a stereotyped object or situation, a method of knowledge representation in AI.

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Hyponymy is the "is-a-kind-of" relation: A is a hyponym of B when A is subordinate to B (rose is a hyponym of flower). Part-whole is meronymy.

Explanation

WordNet is a lexical database linking words by relations such as synonymy and hyponymy, a classic large semantic network.

Explanation

Turing showed that a simple machine manipulating symbols (such as 0 and 1, a binary system) can carry out any algorithmic task.

Explanation

Expert systems are expected to be reliable, understandable, highly responsive and high-performing, so "unreliable" is not a characteristic.

Explanation

Expert systems can advise, explain and suggest alternative solutions, but they cannot possess human abilities, refine their own knowledge or replace human decision makers.

Explanation

JESS is the Java Expert System Shell, a rule engine and expert-system shell written in Java.

Explanation

Secure e-commerce transactions need integrity (data not altered), confidentiality (data not disclosed) and overall security such as authentication, so all apply.

Explanation

Public key cryptography uses a pair of different keys (public and private), so it is asymmetric; symmetric cryptography uses one shared key.

Explanation

Hacking is a logical/cyber threat carried out through software and networks; storm, fire and flood are physical threats to equipment.

Explanation

SSL secures the connection, SET secures card payments, and S-HTTP secures individual HTTP messages, so all are used for secure communication channels.

Explanation

MMID (Mobile Money Identifier) is a 7-digit number issued by banks for IMPS mobile money transfers.

Explanation

Unwanted, unsolicited or unclassified email is called junk mail (also commonly called spam); the key uses "junk mail".

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Animation is a sequence of drawn images shown in quick succession to simulate motion of objects.

Explanation

The key treats computer graphics, pixel-based images and camera (image acquisition) mechanisms as all related examples of digital image processing, so "all of the mentioned" is chosen.

Explanation

Aliasing is caused by high frequencies above the sampling limit, so it is reduced by smoothing (blurring) the image to cut those components before sampling.

Explanation

In the standard sequence of image processing (Gonzalez), compression is followed by morphological processing, then segmentation and representation and description.

Explanation

JPEG stands for Joint Photographic Experts Group, the committee that created the image compression standard.

Explanation

Contrast stretching expands a narrow range of input gray levels to cover the full range, increasing the dynamic range of the image.

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Multimedia tools (computer graphics, animation, sound) are widely used to create special effects in movies.

Explanation

Classroom teaching aims at all-round development of the learner's personality, not just giving information, covering the syllabus or passing exams.

Explanation

Thorndike's laws of learning are the law of readiness, the law of exercise and the law of effect.

Explanation

Combining explanation (lecture) with showing (demonstration) is a complete teaching method; drilling and illustration are techniques or devices.

Explanation

When learners know the objectives they understand what to achieve and can take part actively in the learning process.

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The psychomotor domain covers skills needing body movement and coordination, so map making, project making and playing all belong to it.

Explanation

Heuristic comes from the Greek "heurisko", I find out; in the heuristic method (Armstrong) students investigate and discover for themselves.

Explanation

The deductive approach goes from general to specific: a rule is given first and then applied to examples.

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The inductive method starts from specific examples and observations and moves to a general rule or principle.

Explanation

Maria Montessori introduced didactic apparatus, self-correcting materials that train the senses through activity.

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In modern lesson planning the student is the central point; objectives, methods and activities are planned around the learner.

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Letting children brainstorm and make intuitive guesses encourages divergent thinking and exploration, which builds problem-solving skills.

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Experiential learning (Kolb) is learning through experience followed by reflection, so critical reflection on the experience is central.

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The key takes both as true but treats R as not the reason for A: a meaningful environment is needed for engagement, while the claim that all children are intrinsically motivated does not by itself explain it.

Explanation

A good test must be valid, reliable and objective; ambiguity makes items unclear and is a defect, not a characteristic.

Explanation

The proverb means that if a child is not punished for wrongdoing he will be spoiled, i.e. undesirable behaviour should be punished.

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A textbook gives organised content and exercises that help teachers and students reach the learning objectives of the course.

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Textbooks support study by developing memory and reasoning; the claim that they distract students from studies is not true.

Explanation

Teacher effectiveness is judged by teacher abilities (presage), classroom behaviour (process) and learning outcomes (product), so all apply.

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Adjustment is a personal process, so the teacher is primarily responsible for his or her own adjustment to the job and setting.

Explanation

The teacher-centred method is formal, the teacher dominates (sovereignty) and, in the key's view, it tends to ignore new technology, so all apply.

Explanation

Good evaluation should be valid, reliable and objective; subjectivity (personal bias in scoring) is a weakness, not a quality.

Explanation

The BSEB Matriculation exam is set by an external board, judges against set standards and is held at the end of the course (summative), so all apply.

Explanation

Grading can be absolute (fixed mark ranges) or relative (based on the group's performance), so the grading system involves both types.

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A syllabus is an outline of the content to be taught in a subject; curriculum is the broader set of all learning experiences.

Explanation

The hidden curriculum is the unwritten values, norms and beliefs learnt from the school and classroom atmosphere.

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The student's interest is a psychological factor; salary and caste are not psychological, and the nature of the subject is a content factor.

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Teaching follows the maxims simple to complex, concrete to abstract and known to unknown, so all apply.

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Maturity, readiness and level of aspiration affect learning; a geographical boundary is not a teaching-learning factor.

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Mnemonics are memory aids such as rhymes or acronyms (e.g. VIBGYOR) that help learners remember information.

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Hands-on learning builds new skills by doing and often involves exploring real objects and nature, so both benefits apply.

Explanation

The Indian League was founded in 1875 in Calcutta by Sisir Kumar Ghosh, with Sambhu Charan Mukherjee among its leaders; it was later replaced by the Indian Association (1876).

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Muga silk, a golden silk from the Antheraea assamensis silkworm, is produced almost entirely in Assam and has a GI tag.

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Devaluation makes a country's goods cheaper abroad and imports dearer, so exports rise and imports fall.

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Champaran Satyagraha (1917) was Gandhi's first civil disobedience movement in India, against the tinkathia system forced on indigo tenant farmers in Bihar, so both statements are correct.

Explanation

The Mother Tongue Survey of India was conducted by the Office of the Registrar General and Census Commissioner, which is under the Ministry of Home Affairs.

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Methane and carbon dioxide trap infrared heat and are greenhouse gases; nitrogen does not absorb infrared and is not one.

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The key gives two main components; descriptions of integrated waste management vary between sources, so this item follows the source's own classification.

Explanation

Subsistence farming, especially shifting (slash-and-burn) cultivation, clears new forest patches repeatedly, so it is treated as the main cause of deforestation.

Explanation

El Niño is the abnormal warming of surface waters in the central and eastern equatorial Pacific Ocean, which affects weather worldwide, including India's monsoon.

Explanation

12 × 18000 = 216000; remaining 8 cycles earned 300000 - 216000 = 84000, so the average is 84000 / 8 = Rs. 10500.

Explanation

11.71 - 0.86 = 10.85; 10.85 + 1.78 = 12.63; 12.63 - 9.20 = 3.43.

Explanation

Let the numbers be 13a and 13b with a + b = 12 and a, b co-prime: (1, 11) and (5, 7) only, so there are 2 pairs.

Explanation

tan θ = height / distance; increasing both by 20% leaves the ratio unchanged, so the angle of elevation stays the same.

Explanation

Umbrage is a synonym of offense, so elation pairs with its synonym jubilance (great joy).

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Tail, trunk and feather are parts of animals or birds, while fir is a whole tree (a conifer), so it is the odd one.

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The series lists consecutive prime numbers: 7, 11, 13, 17, 19, so the next prime is 23.

Explanation

Each pair of letters is swapped: SP-ID-ER becomes PS-DI-RE, so CO-MM-ON becomes OC-MM-NO = OCMMNO.

Explanation

The only daughter of the woman's father is the woman herself, so the man's wife is the woman: he is her husband.