Computer Science — MCQ Questions & Answers

Explanation — In computer graphics, a transformation simply means changing the position, orientation, or size of an object.To create an animation (motion), you must apply transformations frame by frame over time:Translation: Moving an object from one position $(x, y)$ to another $(x', y')$. This produces straight-line movement (e.g., a car driving across the screen).Rotation: Turning an object around a specific pivot point or axis by an angle $\theta$ (e.g., a spinning wheel).Scaling: Increasing or decreasing an object's dimensions (e.g., an object appearing to move closer or farther away).By applying these mathematical operations continuously across successive frames, the computer simulates realistic motion.

Explanation — HTTP is an application-layer protocol that defines the rules for communication between a web client (such as a browser) and a web server. Basic flow: Client/Browser → HTTP Request → Web Server → HTTP Response → Client/Browser Key points for DSSSB CS HTTP = HyperText Transfer Protocol Layer = Application Layer Purpose = Communication between web clients and web servers Request methods = GET, POST, PUT, DELETE, etc. Common port = 80 HTTPS = HTTP secured using TLS HTTP is stateless — each request is independent unless mechanisms such as cookies/sessions are used.

Explanation — Core Concept: CGI (Common Gateway Interface) CGI (Common Gateway Interface) is a standard interface that defines how a web server communicates with external application programs/scripts to generate dynamic web content. Basic flow: Client/Browser → Web Server → CGI → Application Program → Web Server → Client Key Points for DSSSB CS CGI = Common Gateway Interface Purpose: Communication between a web server and application programs Used for: Generating dynamic web pages/content CGI acts as an interface/bridge between the web server and external programs. Programs can be written in languages such as C, C++, Perl, Python, etc. CGI is not a programming language; it is a standard/interface. CGI programs are commonly called CGI scripts. ⭐ Exam Shortcut Web Server ↔ Application Program = CGI Web Browser/Client ↔ Web Server = HTTP

Explanation — In software engineering, designing a large application happens in layers—from a 30,000-foot view down to line-level logic. This top-down refinement follows three clear stages: 1. System Design (Highest Abstraction): Looks at the product as a whole from the highest level. Identifies overall user requirements, hardware/software boundaries, platform needs, and external environment interactions without worrying about internal code structure. 2. Architectural Design (Sub-System Level): Takes the system concept and splits it into discrete sub-systems, major components, and databases. Defines how these sub-systems communicate with each other (interfaces, protocols, and data flow). 3. Detailed Design / Low-Level Design (Module Level): Focuses on individual modules within each sub-system. Specifies exact data structures, internal algorithms, function signatures, and interface logic so developers can start coding directly.

Explanation — The question asks which software development model cannot handle changing requirements once development has begun. The key clue word is INCOMPATIBLE (meaning it does not fit or work well) with changing requirements. (Easy Way to Remember) Think of software models like building styles: Linear Model (Waterfall): Like pouring concrete in a staircase.You must finish Step 1 (Requirements) completely before moving to Step 2 (Design), then Step 3 (Coding), and Step 4 (Testing). You cannot climb back up without destroying the structure. If a client changes their mind halfway through, the whole process breaks because requirements are frozen at the very beginning. Therefore, it is incompatible with changes. Evolutionary / Agile / Incremental Models: Like playing with Lego bricks. You build small features piece-by-piece, show them to the user, take feedback, and adapt as you go. They are specifically designed to welcome change at any point. Quick Exam Hook Fixed requirements + strictly sequential - Linear (Waterfall) Changing / evolving requirements - Agile, Evolutionary, or Incremental

Explanation — To convert from Octal to Gray Code, follow two simple steps: Octal $\to$ Binary $\to$ Gray Code. Step 1: Convert Octal to Binary (3 bits per octal digit)$7 \to 111$$4 \to 100$$3 \to 011$Combined binary: $111100011_2$ Step 2: Convert Binary to Gray Code (XOR adjacent bits)Keep the first bit (MSB) as it is:First Gray bit = 1XOR each bit with the next bit ($0 \oplus 0 = 0$, $1 \oplus 1 = 0$, different = $1$):$1 \oplus 1 = \mathbf{0}$$1 \oplus 1 = \mathbf{0}$$1 \oplus 1 = \mathbf{0}$$1 \oplus 0 = \mathbf{1}$$0 \oplus 0 = \mathbf{0}$$0 \oplus 0 = \mathbf{0}$$0 \oplus 1 = \mathbf{1}$$1 \oplus 1 = \mathbf{0}$ Resulting Gray code: $100010010$

Explanation — A compiler is a translator that converts source code written in a high-level programming language into object code (target code), which can then be linked and executed. Exam concept: Source Code → Compiler → Object/Target Code Example: C/C++ source program (.c / .cpp) → Compiler → Object code (.obj / .o) Exam shortcut “Produces object/target code” → Compiler “Translates and executes line by line” → Interpreter So for a DSSSB Computer Science question, Compiler is the correct answer.

Explanation — A subscription is the digital equivalent of a newspaper delivery or gym membership: Instead of buying a product once and owning it forever, the customer pays a recurring fee at set time intervals (every month, quarter, or year) to keep continuous access to the service. If payments stop, access stops. Everyday Examples: Netflix, Spotify, cloud storage (Google One), or SaaS software (Microsoft 365).

Explanation — RISC — Simple Instructions RISC = Reduced Instruction Set Computer RISC gives the processor small and simple instructions. 👉 Example: Instead of giving one worker a complicated job, we give them small, easy tasks one by one. Uses simple instructions Instructions are usually fixed-length Hardware is simpler Generally requires fewer transistors Usually more power-efficient Common in smartphones, tablets, smartwatches ARM processors are based on the RISC approach Remember: RISC → Reduced instructions → Reduced complexity → Reduced power 🔴 CISC — Complex Instructions CISC = Complex Instruction Set Computer CISC provides complex instructions that can perform multiple operations. 👉 Think of it as giving the worker one big instruction that requires several steps internally. Uses complex instructions Instructions can be variable-length Hardware is more complex Complex instructions may require multiple clock cycles Traditionally associated with x86 processors used in PCs and laptops Remember: CISC → Complex instructions → Complex hardware 🧠 One-Line Trick RISC = Simple + Fast + Power Efficient CISC = Complex + Powerful Instructions Important: Don't memorize “RISC always uses one clock cycle” or “CISC always consumes more power” as absolute rules. These are useful exam-level generalizations, not universal rules for every modern processor.

Explanation — RISC — Simple Instructions RISC = Reduced Instruction Set Computer RISC gives the processor small and simple instructions. 👉 Example: Instead of giving one worker a complicated job, we give them small, easy tasks one by one. Uses simple instructions Instructions are usually fixed-length Hardware is simpler Generally requires fewer transistors Usually more power-efficient Common in smartphones, tablets, smartwatches ARM processors are based on the RISC approach Remember: RISC → Reduced instructions → Reduced complexity → Reduced power 🔴 CISC — Complex Instructions CISC = Complex Instruction Set Computer CISC provides complex instructions that can perform multiple operations. 👉 Think of it as giving the worker one big instruction that requires several steps internally. Uses complex instructions Instructions can be variable-length Hardware is more complex Complex instructions may require multiple clock cycles Traditionally associated with x86 processors used in PCs and laptops Remember: CISC → Complex instructions → Complex hardware 🧠 One-Line Trick RISC = Simple + Fast + Power Efficient CISC = Complex + Powerful Instructions Important: Don't memorize “RISC always uses one clock cycle” or “CISC always consumes more power” as absolute rules. These are useful exam-level generalizations, not universal rules for every modern processor.