class 8 chapter 4
Here are the answers for Section A from the Test Yourself page:
A. Choose the correct answer.
The steps in an algorithm must be arranged in a ................................. Order.
Answer: b. Logical
Which of the following characteristics of algorithms indicate that it must end after suitable number of steps.
Answer: d. Finite
Which of the following keywords indicate decision-making?
Answer: c. Both a) and b) (Both
IfandElseare decision-making keywords)
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:
---
## **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)*
---
## **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.
---
## **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**
---
## **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:
---
## **E. Answer the following questions.**
### **1. What is an algorithm? Give one example.**
* **Definition:** An algorithm is a step-by-step procedure or set of well-defined instructions written in clear, simple language to solve a specific problem.
* **Example (Adding two numbers):**
* **Step 1:** Start
* **Step 2:** Take two numbers, $A$ and $B$
* **Step 3:** Calculate $\text{Sum} = A + B$
* **Step 4:** Display $\text{Sum}$
* **Step 5:** Stop
---
### **2. Mention the rules for writing an algorithm.**
* Each step should be clear, unambiguous, and easy to understand.
* Steps must be arranged in a precise, logical sequence.
* It must begin with a **Start** step and end with a **Stop/End** step.
* Statements should be independent of any specific programming language.
* It must produce at least one output and terminate after a finite number of steps.
---
### **3. What is a flowchart?**
* **Answer:** A flowchart is a graphical or visual representation of an algorithm. It uses standard geometric shapes (like ovals, rectangles, diamonds, and parallelograms) connected by directional arrows to illustrate the flow of control and sequence of steps required to complete a task.
---
### **4. What are the advantages and disadvantages of a flowchart?**
* **Advantages:**
* **Easy Communication:** Makes logic easy to understand visually compared to lines of text.
* **Better Debugging:** Helps in identifying and fixing errors easily.
* **Effective Analysis:** Provides a clear blueprint for program design.
* **Disadvantages:**
* **Time-Consuming:** Drawing detailed flowcharts for large programs takes significant time and effort.
* **Difficult to Modify:** Any change in logic often requires redrawing the entire flowchart.
* **Cluttering:** Complex logic leads to messy, complicated diagrams.
---
### **5. Explain Branched Flowchart with an example.**
* **Explanation:** A branched flowchart is a flowchart that includes decision-making points where the path splits into two or more branches based on a condition (Yes/No or True/False).
* **Example:** Checking whether a number is positive or negative.
* *Flow:* **Start** $\rightarrow$ **Input Number ($N$)** $\rightarrow$ **Decision:** Is $N \ge 0$?
* If **Yes** $\rightarrow$ Print "Positive" $\rightarrow$ **Stop**
* If **No** $\rightarrow$ Print "Negative" $\rightarrow$ **Stop**
---
---
## **F. Write algorithms for the below tasks.**
### **1. To prepare a coffee.**
1. **Step 1:** Start
2. **Step 2:** Boil water/milk in a pan.
3. **Step 3:** Add coffee powder and sugar to a cup.
4. **Step 4:** Pour the hot milk/water into the cup.
5. **Step 5:** Stir well.
6. **Step 6:** Serve hot coffee.
7. **Step 7:** Stop
---
### **2. To find the circumference of a circle with a given radius.**
1. **Step 1:** Start
2. **Step 2:** Input/Read the radius ($r$)
3. **Step 3:** Calculate $\text{Circumference} = 2 \times 3.14 \times r$
4. **Step 4:** Display $\text{Circumference}$
5. **Step 5:** Stop
---
### **3. To check if a student has passed or failed the exam. (Condition: A student passes if their marks are 40 or greater.)**
1. **Step 1:** Start
2. **Step 2:** Input/Read the student's marks ($\text{Marks}$)
3. **Step 3:** Check if $\text{Marks} \ge 40$:
* If **True**, print "Pass"
* If **False**, print "Fail"
4. **Step 4:** Stop
---
---
## **G. Draw flowcharts using appropriate symbols.**
### **1. Calculate the product of two even numbers.**
```text
( Start )
│
▼
[ Input Number1, Number2 ]
│
▼
[ Product = Number1 * Number2 ]
│
▼
[ Display Product ]
│
▼
( Stop )
```
* **Shapes to use when drawing:**
* `Start` & `Stop`: **Oval**
* `Input` & `Display`: **Parallelogram**
* `Product calculation`: **Rectangle**
---
### **2. To prepare a sandwich.**
```text
( Start )
│
▼
[ Take 2 slices of bread ]
│
▼
[ Apply butter and spread filling ]
│
▼
[ Place the second slice on top ]
│
▼
[ Serve Sandwich ]
│
▼
( Stop )
```
* **Shapes to use when drawing:**
* `Start` & `Stop`: **Oval**
* `Take/Serve`: **Parallelogram**
* `Preparation steps`: **Rectangle**
---
### **3. To show the route from your home to school.**
```text
( Start )
│
▼
[ Leave home and go straight ]
│
▼
< Reached Turn/Crossroad? >
│ │
(Yes) (No)
│ │
▼ ▼
[ Turn Right/Left ] [ Keep going straight ]
│ │
└─────────┬─────────┘
│
▼
[ Reach School Gate ]
│
▼
( Stop )
```
* **Shapes to use when drawing:**
* `Start` & `Stop`: **Oval**
* `Reached Turn/Crossroad?`: **Diamond (Decision)**
* `Action steps`: **Rectangle**
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