DSSSB TGT Computer Science Practice Set 2

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cursor.fetchall() returns the remaining rows as a list of tuples (one tuple per row), or an empty list if no rows are left.

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XML was designed to store and transport data, while HTML was designed to display data.

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Corrected: the book's key says (d). The loop runs for AGE = 5, 11, 17, 23, 29, i.e. 5 times.

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In VBScript, * is evaluated before MOD, and MOD before + and −. 18 MOD 7 = 4 and 4*2 = 8, so 4 + 8 − 10 = 2.

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DELETE FROM table WHERE condition removes matching rows. There is no REMOVE command, DROP removes the whole table, and DELETE * is not valid standard SQL.

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Listing two tables with no join condition gives their Cartesian product: every student paired with every game (3 × 2 = 6 rows), which matches the output.

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Corrected: the book's key says (a), but STOCK S1(S2) calls the copy constructor. A declaration without arguments, like STOCK S2, invokes the default constructor.

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Teacher inherits from Activity, and SUPW inherits from Teacher. A chain of single inheritance like this is multilevel inheritance.

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Corrected: the book's key says (b). The standard order is: analyse the problem, develop an algorithm, code, then test and debug.

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Answer as per the book's key (b): * is binary multiplication and unary dereference. Note that − is also both unary and binary.

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Decreasing access time means going from slowest to fastest: magnetic tape, magnetic disk, main memory, register. Option A wrongly puts cache before main memory.

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Corrected: the book's key says (a). Interrupts are sent by I/O devices and received by the CPU.

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window is the top-level (global) object of the browser object model. document, location and others are its properties.

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Client-side scripts run in the browser and give speed, control of widgets and interactivity. Managing data repositories across systems is done on the server side.

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An fstream opened with ios::in | ios::out allows both reading and writing. ios::read and ios::write do not exist.

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seekg(F.tellg()*N) multiplies the current position by N, which is not the offset of the (N+1)th record. The correct offset is N*sizeof(EMPLOYEE).

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CHR(77) is "M", and & joins strings, so "A" & "M" & "T" gives AMT.

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The book prints option (c) as LOCAL again; it has been replaced with MODULE-LEVEL so only one option is correct.

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In SCAN, the disk arm moves to one end, then reverses, serving requests along the way, like an elevator. C-SCAN, not SCAN, gives more uniform waiting time.

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The banker's algorithm avoids deadlock (by checking for a safe state); it does not prevent it. Prevention means removing one of the four necessary conditions.

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A 16-to-1 MUX has 16 data inputs + 4 select lines = 20 inputs. A PROM needs 2²⁰ words × 1 output bit = 1M × 1.

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Mirroring (RAID 1) keeps a duplicate copy of every disk. It is the simplest form of redundancy but the costliest, because storage is doubled.

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A bridge filters and forwards frames using MAC addresses, so it works at the data link layer (layer 2).

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Zig-zig rotations are the restructuring steps of a splay tree, which move an accessed node up to the root.

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Each row and each column has exactly one piece, and no two pieces share a diagonal. This is a solution to the Eight Queens problem.

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MUX-1 and MUX-2 choose between I3/I2 and I1/I0 using S1, and MUX-3 chooses between their outputs using S0. Four inputs and two select lines make a 4-to-1 multiplexer.

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A bistable multivibrator (flip-flop) has two stable states and stays in either HIGH or LOW until it is triggered.

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An escape sequence is written with two or more characters in the source code, but it represents and stores a single character, so it takes 1 character (1 byte).

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Fidelity is how closely the recorded or reproduced sound matches the original sound.

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In a mesh topology each device has dedicated links to the others, so a single link failure does not affect the network. This gives the highest reliability.

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An IPv4 address is 32 bits = 4 bytes, usually written as four dotted decimal octets.

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E-commerce (electronic commerce) means buying and selling goods and services over the Internet.

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Multiple inheritance means one derived (child) class inherits from two or more base (parent) classes.

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COMMIT, ROLLBACK and SAVEPOINT are transaction control (TCL) commands. SELECT is a data query command.

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Concurrency control keeps data consistent when several users update the database at the same time, preventing lost updates and inconsistent reads.

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If Y is negative, both signs are flipped. The loop then adds X to Z Y times, so Z = X × Y.

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A multiplexer selects one of several inputs and sends it over a single output line, so many data sources can share one transmission line.

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Anti-aliasing smooths the jagged, staircase edges ("jaggies") caused by pixel sampling, which makes text easier to read.

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Shortest Job First runs the shortest tasks first, so the average waiting time is minimised and the most jobs are completed per unit time.

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Anti-aliasing smooths the jagged, staircase edges ("jaggies") caused by pixel sampling, which makes text easier to read.

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Shortest Job First runs the shortest tasks first, so the average waiting time is minimised and the most jobs are completed per unit time.

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24 = 0000 0000 0001 1000. Invert the bits (1111 1111 1110 0111) and add 1 to get 1111 1111 1110 1000, which is −24 in 2's complement.

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A skewed (degenerate) BST is like a linked list, so a search may have to visit all n nodes: O(n) in the worst case.

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In Boolean algebra, + is OR and · is AND. (0+0+0) = 0, so 0 · (0+1+1) = 0. Every other option has both factors equal to 1.

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With LRU and 4 frames: 7, 0, 1, 2 are 4 faults; 3 replaces 7; 4 replaces 1; then 1 replaces 4. All other references are hits, so there are 7 page faults.

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ReDim resizes a dynamic array in VB (ReDim Preserve also keeps its existing contents). Dim only declares the array.

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A consumer first does wait(F) to make sure a full slot exists, then wait(M) for mutual exclusion on the buffer, and only then removes the item.

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Clustered systems join several computers to provide high availability and high-performance computing. In asymmetric multiprocessing the processors are not peers, and multiprocessor does not always mean multicore.

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Each character takes 1 start + 7 data + 1 parity + 1 stop = 10 bits, so 2400 / 10 = 240 characters per second.

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The relational, hierarchical and network models are record-based logical models. The E-R model is an object-based conceptual model.

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Shared (read) locks are compatible with each other, so B's shared-lock request on R is granted immediately.

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A data model is a collection of conceptual tools for describing data, data relationships, data semantics and consistency constraints (Korth).

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Corrected: the book's key says (b). Set difference is neither commutative (R − S ≠ S − R) nor associative.

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The number of equivalence relations on a 4-element set equals the number of its partitions, which is the Bell number B₄ = 15.

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The range is the set of second elements (outputs) of the ordered pairs: {8, 2, −4}.

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Removing B separates {A, D} from {C, E}, and removing C cuts off E. Removing A, D or E leaves the graph connected, so the cut vertices are B and C.

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Spyware secretly monitors a user's activity, such as browsing and keystrokes, and sends that information to a third party in the background. Adware mainly shows unwanted advertisements.

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A*(B+C)/D is evaluated as (A*(B+C))/D. In prefix form this is / * A + B C D.

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In a B-tree of order p, every non-root node has at least ⌈p/2⌉ children. So the maximum height is log base ⌈p/2⌉ of (n+1)/2.

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8 2 3 ^ gives 2³ = 8, then 8 / 8 = 1. Next 2 and 3 are pushed and * gives 6. The stack now holds 1, 6, so the top two elements are 6 and 1.

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37→2, 38→3, 72→2 (taken, goes to 3, then 4), 48→6, 98→0. 11 mod 7 = 4 is taken, so linear probing places 11 at slot 5.

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In optical fibre, light stays inside the glass core by total internal reflection at the core-cladding boundary.

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Demand paging loads a page into memory only when it is referenced, which triggers a page fault.

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This is the subtraction form of Euclid's algorithm: repeatedly subtracting the smaller number from the larger one until both are equal leaves their GCD.

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(A+C)(AB'+AC) = AB' + AC by absorption. Multiplying by (A' + B' + C') gives AB' + AB'C = AB'.

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MOV is a data transfer instruction. JMP and CALL change the flow of control, and CMP is used with jumps to make decisions, so these are program control instructions.

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Emitter-Coupled Logic (ECL) is the fastest logic family, because its transistors never saturate, but it uses a lot of power.

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Each recursive call pushes its return address and local variables onto a stack, so recursion is implemented with a stack.

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Inserting B, I, N, A, R, Y gives root B with A on the left and the chain I → N → R → Y to the right. The longest path B-I-N-R-Y has 4 edges, so the height is 4.

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confirm() shows a dialog with a message and OK and Cancel buttons and returns true or false. alert() has only OK, and prompt() also asks for text input.

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The XML declaration is a processing instruction: <?xml version="1.0"?>. It begins with <?xml and the version value is quoted. Option B is the closest to this form.

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and is a logical operator in Python (as are or and not). in is a membership operator, <= is relational and += is assignment.

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Python identifiers cannot start with a digit or contain spaces, so "1st Name" is invalid.

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A parameter without a default value cannot follow parameters that have default values. def Compu(X=100, Y=10, Z): raises a SyntaxError.

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The csv writer object's writerow() method writes one row (line) to a CSV file. writerows() writes several rows.

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A=100: S=100, A=60. A=60: S=160, A=20. A=20 (still ≥ 20): S=180, A=−20. The condition is now false, so the output is 180.

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pl.plot([5, 2, 3, 1]) draws a line graph, using the indexes 0-3 as x values. bar and scatter give different charts, and pl.line does not exist.

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The degree of a relation is its number of attributes (columns). Cardinality is the number of tuples (rows).

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Observing keenly, making notes and sharing observations encourages active, inquiry-based and collaborative learning.

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Learning by doing (planting seeds and watching them germinate) gives direct experience, which is the most effective way to teach this concept.

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onmouseover fires when the pointer enters the link, and onmouseout fires when it leaves. There are no OnMouseIn or OnMouseExit events.

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open(), close() and prompt() are methods of the window object. name is a property (window.name), not a method.

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The new node's next and prev pointers are set, and the next pointer of the previous node and the prev pointer of the following node are updated. That makes 4 pointer changes.

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The loop must stop at the end of the list or when X is found, so it continues only while P != NULL && P→Element != X. Checking for NULL first also avoids dereferencing a null pointer.

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The NOR gates give (A+B)' and (C+D)', and the AND gate combines them, so the output is (A+B)' · (C+D)'.

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By the absorption law, a + a·b = a(1 + b) = a·1 = a.

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Optical fibre gives high bandwidth over long distances with little loss and no electromagnetic interference, so it is best for linking offices in different cities.

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GSM stands for Global System for Mobile Communication, the 2G digital cellular standard.

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A Trial Balance lists all ledger balances to check that total debits equal total credits, which tests the arithmetical accuracy of the ledger accounts.

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The Sales Book (Sales Journal) records only credit sales of goods. Cash sales go to the Cash Book.

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Fitting a new experience (another dog) into an existing schema is assimilation in Piaget's theory. Accommodation means changing the schema itself.

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Aggression relates to emotions, attitudes and behaviour, which belong to the affective domain of learning.

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The psychomotor domain (doing, action) is also called the conative domain. Cognitive is knowing and affective is feeling.

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In Piaget's sensorimotor stage (birth to 2 years), infants learn about the world through their senses and motor actions.

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Sigmund Freud described the latency period (about 6 years to puberty) as one of the stages of psychosexual development.

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Vygotsky said that private speech (talking to oneself) helps children guide and regulate their own thinking and behaviour.

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In the 2001 revision by Anderson and Krathwohl, the nouns were changed to verbs, and synthesis became "creating", placed at the top level.

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Private-school students could continue studying because they had better access to digital devices and the internet. The gap is a technological (digital divide) factor.

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Adolescents feel that everyone is watching them (Elkind's "imaginary audience"), so they become very self-conscious.

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In childhood (early childhood), imagination is strong, so children enjoy fictional stories such as fairy tales the most.