Computer Science Previous Year Questions (page 5)

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Nulls do not reduce storage space, so (D) is false. The other statements are true: heavy normalization means more joins, foreign keys enforce referential integrity, and a primary key uniquely identifies a row.

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The accumulator holds an operand and stores the result of arithmetic and logic operations. The program counter holds the next instruction's address, and the stack pointer holds the top of the stack.

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A 14-unit job with a 2-unit quantum runs in 7 slices. A switch is counted between slices, giving 7 − 1 = 6 context switches.

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Aging gradually raises the priority of processes that have waited a long time. This prevents starvation (indefinite blocking) of low-priority jobs.

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IN matches any value in the list, so the query returns customer_name and telephone of customers whose city is Jaipur, Delhi or Agra. A customer cannot live in all three cities at once.

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ROM keeps its contents when power is off, so it is non-volatile. RAM and cache lose their data when power is removed.

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By De Morgan's law, (A·B)' = A' + B'.

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list() on a string makes a list of its individual characters, so list('PEACE') gives ['P', 'E', 'A', 'C', 'E'].

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range(6, 1, −2) gives 6, 4 and 2, so the loop runs 3 times. print(end='*$$') prints only '*$$' with no newline, giving *$$*$$*$$.

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Python's membership operators are 'in' and 'not in'. 'is' is an identity operator, and 'or'/'not' are logical operators.

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str.partition(sep) always returns a 3-tuple: the part before the separator, the separator, and the part after it. split() can return any number of parts.

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Optical fibre carries light signals. This gives very high bandwidth and long distances, and it is immune to electromagnetic interference, but it is expensive.

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ARPANET stands for Advanced Research Projects Agency Network. It was the US Department of Defense network that led to the Internet.

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UNIX inodes use an extended indexed scheme: 12 direct block pointers plus single, double and triple indirect blocks. This lets very large files be addressed.

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In Flash, a fade effect is made with a motion tween that changes the symbol's alpha (transparency) from 100% to 0%, so the symbol gradually disappears.

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3NF removes transitive dependencies, where a non-key attribute depends on another non-key attribute. 2NF removes partial dependencies.

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Digital drawing is a graphics application. Payroll, HR management and invoicing all store and manage records in databases.

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With public inheritance, protected members stay protected and public members stay public in the derived class. So Name is protected and Readdata() is public. The private AadharNo is not accessible in Student.

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ifstream opens a file for input (reading). ofstream is for writing. ios::read is not a valid mode.

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Visual Basic variable names cannot contain spaces, so "First Name" is invalid. The keyed answer treats the other names as valid.

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VB's default (binary) string comparison uses character codes. 'C' (67) is less than 'c' (99), so "Care" < "care" is true.

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A stack machine takes its operands implicitly from the top of the stack. So instructions like ADD need no address fields, which makes them zero-address instructions.

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With FIFO and 3 frames: 7, 0, 1, 2 are faults (4 so far), 0 is a hit, then 3, 0, 4, 2, 3 are all faults. That gives 9 page faults.

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CSS describes how HTML elements are displayed (presented), not how they are stored within tags. So (C) is false.

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XML separates data from HTML, so it does not separate design (presentation) from HTML. The other options are standard XML features.

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A foreign key is an attribute in one table that refers to the primary key of another table, linking the two tables.

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DROP TABLE EMPLOYEE removes the table's structure and all its data. DELETE FROM only removes rows and keeps the structure.

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In a VB Select Case statement, multiple values in one Case are separated by commas, for example Case 1, 3, 5.

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Keywords (reserved words) such as If, Dim and Loop have a predefined meaning in Visual Basic, so they cannot be used as variable names.

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With a quantum of 4: P1 runs 0–4, P2 runs 4–7, P3 runs 7–10, then P1 runs 10–30. Waiting times are P1 = 6, P2 = 4, P3 = 7. The average is 17/3 ≈ 5.66 units.

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The full sequence starts with designing the solution, then writing code, compiling it to object code, linking libraries, loading into memory and executing. The other options leave out design or linking.

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Encapsulation wraps data (characteristics) and the functions that act on it (behaviour) into one unit, the class. Data hiding and abstraction are results of this.

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An embedded system is electronics and software built into a product for a dedicated function, such as a washing machine or microwave controller, rather than a general-purpose computer.

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Bandwidth is the transmission capacity of a channel, meaning how much data it can carry per unit time, measured in bps or Hz.

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An internal computer bus moves data in parallel over very short distances, so it gives a far higher data rate than telephone lines, modems or leased lines.

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An XML parser reads an XML document and turns it into an XML DOM object (a tree) that programs such as JavaScript can access and change.

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Capacity = tracks per side × sides × sectors per track × bytes per sector. So sectors per track = 21,504,000 ÷ (600 × 2 × 512) = 21,504,000 ÷ 614,400 = 35.

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Answer as per the book's key (b).

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In a Schmitt trigger inverter, the output goes HIGH to LOW when a rising input crosses the upper trip point, 2.8 V. It goes LOW to HIGH when a falling input crosses the lower trip point, 1.8 V.

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The upper four OSI layers (Transport, Session, Presentation, Application) are host-to-host (end-to-end) layers. The lower layers handle hop-by-hop delivery over the network.

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A binary storage cell with input, output and Read/Write control lines is the basic building block of a memory. Each cell stores one bit, which is read or written as the control lines select.

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JavaScript variables can be declared with var, and JavaScript is untyped (dynamically typed), so the same variable can hold any type. Both statements are true.

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A run-time error raises an exception, an abnormal condition while the program runs. Syntax errors are caught at compile time.

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GIF is a compressed, widely supported image format made for the web. BMP and TIFF files are large and not suited to web pages, and HTML is not a graphics format.

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In classic ASP (VBScript), variables are declared with the Dim statement, for example Dim name.

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Corrected: the book's key says (b). HAVING can be used without GROUP BY (the whole result is one group), and WHERE is applied before HAVING, so both statements are false.

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In a synchronous parallel-load shift register, all 8 bits enter their flip-flops at the same time. So a single clock pulse loads the whole byte.

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AB → C holds because every (A, B) pair is unique, and B → C holds because b1→c1, b2→c2 (twice) and b3→c4. B → D fails (b2 gives d2 and d3), as do D → A and A → D.

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Frequencies from about 1 GHz to 300 GHz are microwaves, used for satellite, radar and point-to-point links. Radio waves are below this range and infrared is above it.

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Depreciation spreads (allocates) the cost of a fixed asset over its useful life, matching the expense to the periods that benefit from the asset.