class 8 chapter 4

 Here are the answers for Section A from the Test Yourself page:

A. Choose the correct answer.

1. The steps in an algorithm must be arranged in a ................................. Order.

   • Answer: b. Logical

2. Which of the following characteristics of algorithms indicate that it must end after suitable number of steps.

   • Answer: d. Finite

3. Which of the following keywords indicate decision-making?

   • Answer: c. Both a) and b) (Both If and Else are decision-making keywords)

4. In a flowchart, implementation of a loop is shown as which of the following?

• Answer: a. Backward arrow

Here are the solutions for the page shown in the image:

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## **A. Choose the correct answer (Continued from Q4)**

5. **For which of the following situation, use of flowcharts is suggested?**

* **Answer:** **c. Short, simple algorithms** *(Flowcharts become cluttered and difficult to manage for very complex or long programs)*

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## **B. Fill in the blanks.**

*(Word Bank provided: Algorithm, Circle, Flowchart, Oval, Diamond)*

1. A well-defined, unambiguous set of instructions to solve a problem is called a/an **Algorithm**.

2. A **Diamond** shape is used to show decision-making in a flowchart.

3. The **Oval** symbol is used to indicate the beginning or end of a program.

4. **Circle** joins a flowchart from one page to another. *(Connector symbol)*

5. After writing an algorithm, a **Flowchart** is drawn which is converted into a program.

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## **C. State whether the statements are True or False.**

1. A flowchart is a graphical representation of an algorithm.

* **Answer:** **True**

2. An algorithm must always terminate after a finite number of steps.

* **Answer:** **True**

3. Flowcharts are used only in mathematics.

* **Answer:** **False**

4. All flowcharts begin with the START symbol.

* **Answer:** **True**

5. An Algorithm is always written in a programming language.

* **Answer:** **False** *(Algorithms are typically written in natural language or pseudocode)*

6. Algorithms and flowcharts are essential tools for problem solving in computer science.

* **Answer:** **True**

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## **D. Identify the type of each instruction and sort it under the correct flowchart symbol category**

| Symbol Category | Shape | Statements |

| --- | --- | --- |

| **Start / Stop (Terminal)** | **Oval** | **1.** Start<br>

<br>**6.** Stop<br>

<br>**10.** End<br>

<br>**20.** Stop the process |

| **Input / Output** | **Parallelogram** | **2.** Enter your name<br>

<br>**5.** Display the final result<br>

<br>**7.** Input the age of the user<br>

<br>**11.** Print "Login Successful"<br>

<br>**14.** Show "Invalid input. Try again"<br>

<br>**16.** Show "Thank you!"<br>

<br>**17.** Input username and password |

| **Processing** | **Rectangle** | **3.** Calculate the sum of two numbers<br>

<br>**8.** Multiply marks by 100 and divide by total marks<br>

<br>**12.** Add item to shopping cart |

| **Decision** | **Diamond** | **4.** Is the number greater than 50?<br>

<br>**9.** Check if the password is correct<br>

<br>**13.** Is the entered amount valid?<br>

<br>**19.** Decide if the answer is correct |

| **Connector** | **Circle** | **15.** Connect to the next step<br>

<br>**18.** Go to next step |

Here are clear and structured answers for sections **E**, **F**, and **G** from the page:

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E. Answer the Following Questions

1. What is an algorithm? Give one example.

Definition: An algorithm is a step-by-step procedure or a set of well-defined instructions written in clear and simple language to solve a specific problem.

Example: Adding Two Numbers

1. Step 1: Start
2. Step 2: Take two numbers, A and B.
3. Step 3: Calculate Sum = A + B.
4. Step 4: Display the Sum.
5. Step 5: Stop.

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2. Mention the rules for writing an algorithm.

The rules for writing an algorithm are:

• Each step should be clear, unambiguous, and easy to understand.
• The steps must be arranged in a logical sequence.
• It should begin with a Start step and end with a Stop/End step.
• It should produce at least one output.

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3. What is a flowchart?

A flowchart is a graphical or visual representation of an algorithm.

It uses standard symbols such as ovals, rectangles, diamonds, and parallelograms connected by arrows

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4. What are the advantages and disadvantages of a flowchart?

Advantages:

• Easy Communication: It makes the logic of a program easy to understand visually.
• Better Debugging: It helps in identifying and correcting errors.
• Effective Analysis: It provides a clear plan or blueprint for designing a program.

Disadvantages:

• Time-Consuming: Drawing detailed flowcharts for large programs requires time and effort.
• Difficult to Modify: Changes in logic may require redrawing parts of the flowchart.
• Cluttering: Complex programs can result in complicated and difficult-to-read flowcharts.

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5. Explain a Branched Flowchart with an example.

A branched flowchart is a flowchart that contains a decision-making point where the flow divides into two or more branches depending on a condition.

Example: Checking whether a number is positive or negative

Flow:

Start → Input Number (N) → Is N ≥ 0?

• If Yes → Display "Positive" → Stop
• If No → Display "Negative" → Stop

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F. Write Algorithms for the Following Tasks

1. To prepare a coffee

1. Step 1: Start.
2. Step 2: Boil water or milk in a pan.
3. Step 3: Add coffee powder and sugar to a cup.
4. Step 4: Pour the hot milk or water into the cup.
5. Step 5: Stir well.
6. Step 6: Serve the hot coffee.
7. Step 7: Stop.

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2. To find the circumference of a circle with a given radius

1. Step 1: Start.
2. Step 2: Input the radius (r).
3. Step 3: Calculate Circumference = 2 × 3.14 × r.
4. Step 4: Display the circumference.
5. Step 5: Stop.

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3. To check if a student has passed or failed the exam

Condition: A student passes if the marks are 40 or greater.

1. Step 1: Start.
2. Step 2: Input the student's marks.
3. Step 3: Check whether Marks ≥ 40.
4. Step 4: If the condition is true, display "Pass".

Otherwise, display "Fail".

5. Step 5: Stop.

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G. Draw Flowcharts Using Appropriate Symbols

1. Calculate the product of two even numbers

Flow:

Start → Input Number1 and Number2(even) → Calculate Product = Number1 × Number2 → Display Product → Stop

Symbols to use:

• Start/Stop: Oval
• Input/Display: Parallelogram
• Calculation: Rectangle

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2. To prepare a sandwich

Flow:

Start → Take two slices of bread → Apply butter and spread the filling → Place the second slice on top → Serve Sandwich → Stop

Symbols to use:

• Start/Stop: Oval
• Input/Output or serving information: Parallelogram
• Preparation/Processing steps: Rectangle

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3. To show the route from your home to school

Flow:

Start → Leave home and go straight → Reached Turn/Crossroad?

• Yes → Turn Right/Left → Reach School Gate → Stop
• No → Keep going straight → Check again

Symbols to use:

• Start/Stop: Oval
• Decision: Diamond
• Action/Process steps: Rectangle
• Arrows: Show the direction of flow