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: $100010010$