Viva Questions - Class 8 - Decision Control Structure
Viva Questions — Decision Control Structure
Be Confident, Be Prepared, Shine in Your Viva! This comprehensive guide contains 20 essential Viva Questions and Answers for your Decision Control Structure oral exam. Read carefully, practice speaking aloud, and you'll ace your viva!
Introduction
A Viva Voce is an oral examination where your teacher tests your knowledge through spoken questions. Decision Control Structure viva covers if statements, operators, and best practices — all foundational programming concepts!
Motivational Tip
Think of viva as a friendly chat about programming with your teacher. You know this stuff — you just need to speak it out! Take a deep breath, smile, and show your knowledge.
What is Decision Control Structure?
A Decision Control Structure is a programming construct that allows a program to make decisions and execute different code based on conditions.
Key Points to Remember
Essentials
- ✅ Makes program smart.
- ✅ Executes code conditionally.
- ✅ Uses if, if-else, else-if statements.
- ✅ Uses comparison operators.
- ✅ Uses logical operators.
- ✅ Essential in every program.
20 Viva Questions and Answers
Question 1
What is a decision control statement?
Answer: A decision control statement is a statement that allows a program to make decisions and execute different code based on conditions.
Question 2
What is if statement?
Answer: An if statement
executes code only if the given condition is true.
Syntax: if (condition) { statements; }
Question 3
What is if-else statement?
Answer: An if-else
statement executes one block of code if the condition is
true, and another block if it's false.
Question 4
What is nested if?
Answer: A nested if is an
if statement placed inside another
if statement.
Question 5
What is else-if ladder?
Answer: An else-if ladder is a structure that checks multiple conditions in sequence using else-if blocks.
Question 6
What is the syntax of if?
Answer:
if (condition) { statements; }
The condition must be in parentheses, and statements
are inside braces.
Question 7
What does == operator do?
Answer: The == operator
compares two values for equality. If both are equal, it
returns true; otherwise, false.
Question 8
What is the difference between = and ==?
Answer:
=is assignment — it assigns a value.==is comparison — it compares two values.
Question 9
Name three logical operators.
Answer:
&&— AND||— OR!— NOT
Question 10
What is the use of && operator?
Answer: The &&
(AND) operator returns true only when both
conditions are true.
Example: if (age >= 18 && hasID)
Question 11
What is the use of || operator?
Answer: The || (OR)
operator returns true when at least one
condition is true.
Example: if (day.equals("Sat") || day.equals("Sun"))
Question 12
What does ! operator do?
Answer: The ! (NOT)
operator reverses the condition — TRUE becomes FALSE
and vice versa.
Example: if (!(x == 0)) means "if x is not
equal to zero".
Question 13
Give one comparison operator.
Answer: Common comparison operators are:
> (greater than), <
(less than), >= (greater than or equal
to), <= (less than or equal to),
== (equal to), != (not equal
to). Give any one!
Question 14
What is a Boolean expression?
Answer: A Boolean expression is an
expression that evaluates to either true
or false.
Example: (x > 5) is a Boolean expression.
Question 15
Why do we use braces { } in if?
Answer: We use braces to group multiple statements together. Even for a single statement, using braces is a best practice — it prevents bugs when we add more code later.
Question 16
Can we use if without else?
Answer: Yes, the else
block is optional. If only if is used,
nothing happens when the condition is false.
Question 17
When does else block execute?
Answer: The else block executes only
when the if condition is false.
Question 18
What is a common error in decision statements?
Answer: The most common error is using
= (assignment) instead of ==
(comparison). For example, if (x = 5)
assigns 5 to x instead of comparing!
Question 19
Give an example of if-else in real life.
Answer: "If it rains, take an umbrella.
Else, don't take one." This is a real-life if-else
decision.
Other examples: "If age is 18 or above, allow to vote.
Else, don't allow."
Question 20
What is the output when age = 18 and we check age >= 18?
Answer: The output is TRUE
— because 18 is equal to 18, the condition
age >= 18 is satisfied.
Quick Code Examples
Example 1: if Statement
if (age >= 18) {
System.out.println("Adult");
}Example 2: if-else Statement
if (num > 0) {
System.out.println("Positive");
} else {
System.out.println("Non-positive");
}Example 3: else-if Ladder
if (marks >= 90) {
grade = "A";
} else if (marks >= 75) {
grade = "B";
} else {
grade = "C";
}Example 4: Nested if
if (age >= 18) {
if (hasID) {
System.out.println("Can vote");
}
}Example 5: Logical Operators
// AND
if (age >= 18 && hasID) {
System.out.println("Eligible");
}
// OR
if (day.equals("Sat") || day.equals("Sun")) {
System.out.println("Weekend");
}
// NOT
if (!isRaining) {
System.out.println("Go out!");
}Viva Preparation Tips
Before the Viva
- 💡 Understand concepts, don't just memorize.
- 🎤 Practice speaking answers aloud.
- 💬 Give examples for each concept.
- 💻 Show sample code when asked.
- 😊 Be confident and smile.
- 🙋 Ask if you don't understand.
- 🙏 Thank the teacher after viva.
- 📚 Review your practical activities.
During the Viva
Confidence Tips
- 😊 Smile and greet politely.
- 👂 Listen to the full question.
- 💭 Take a moment to think.
- 🎤 Speak clearly and confidently.
- 👀 Maintain eye contact.
- 🎯 Give short, focused answers.
- 💻 Give code examples when possible.
- 🙏 Say "I'm not sure" if unsure — don't guess wildly.
- 💪 Stay calm if you make a mistake.
- 🙌 Thank the teacher at the end.
Common Mistakes to Avoid
Don't Do These!
- ❌ Confusing = with ==
- ❌ Forgetting else block
- ❌ Missing braces { }
- ❌ Wrong operator use
- ❌ Not testing edge cases
- ❌ Memorizing without understanding
- ❌ Being too nervous
- ❌ Not giving examples
Bonus Viva Questions
Extra Practice
- Q. What is a conditional statement? → A statement that executes based on a condition.
- Q. What is a switch statement? → An alternative to else-if ladder for multi-way branching.
- Q. What is the modulo operator (%)? → Gives the remainder of division.
- Q. How do you check if a number is even? → Use `if (num % 2 == 0)`.
- Q. What is short-circuit evaluation? → In &&, if first is false, second isn't checked.
- Q. Can if-else be replaced with ternary operator? → Yes, using `? :` syntax.
- Q. What's the ternary operator? → `condition ? valueIfTrue : valueIfFalse`.
- Q. What's a truth table? → A table showing all possible outcomes of logical operations.
- Q. Which is faster: if-else or switch? → Switch is often faster for many conditions.
- Q. What's a dangling else? → An else that could match multiple ifs (use braces to fix).
Did You Know?
Fun Fact
Decision statements are used everywhere — games, apps, banking systems, weather apps, ATM machines, traffic lights! Every "if this, then that" in software uses decision statements. You're learning something universal!
Sample Viva Conversation
Teacher: "Good morning! What is a
decision control statement?"
You: "Good morning, ma'am. A decision
control statement allows a program to make decisions and
execute different code based on conditions."
Teacher: "Give me an example."
You: "Yes, ma'am. For example, we can
write: if (age >= 18) print('Adult');
This checks if age is 18 or more, and if true, prints
Adult."
Teacher: "Excellent! What's the
difference between = and ==?"
You: "= is assignment, which gives a
value to a variable. == is comparison, which checks if
two values are equal."
Teacher: "Well done!"
FAQs About Viva
Q1. How long is the viva?
Typically 5-15 minutes per student, covering key concepts.
Q2. What if I don't know an answer?
Say politely: "I'm not sure, ma'am/sir" — don't guess wildly. It's better to be honest than wrong.
Q3. Should I memorize all the code?
No! Understand the concepts. If you understand, you can write code on the spot.
Q4. Can I take my code notes?
Usually not. Practice writing simple examples from memory.
Q5. What if the teacher asks a follow-up question?
Listen carefully and answer to the best of your ability. Take a moment to think.
Q6. Should I speak in English?
Yes, generally. But use your first language if you feel stuck for a technical term — the teacher will understand.
Q7. How do I overcome nervousness?
Deep breaths, practice with friends, remember the teacher wants you to succeed!
Q8. What if I make a mistake?
Stay calm. Correct yourself politely: "Actually, I think it's..." Show you can self-correct.
Key Takeaways
- Decision statements make decisions in programs.
- Types: if, if-else, nested if, else-if ladder.
- Comparison operators: ==, !=, >, <, >=, <=.
- Logical operators: && (AND), || (OR), ! (NOT).
- = is assignment, == is comparison.
- Use braces { } for grouping statements.
- else block is optional.
- Practice speaking answers aloud.
- Give examples during viva.
- Be confident and smile!
Key Takeaway
Prepare well, be confident, and speak clearly!
You will shine in your viva!
Decision control structures are the foundation of
programming. Master them, and you'll be able to write
any complex program. Your viva is a chance to show what
you've learned — go for it!
Remember: Learn Today, Lead Tomorrow!
Practice Makes Perfect! 🌟
⭐ CODE SMART, THINK CLEAR, WRITE BETTER! ⭐
Best of Luck! Take a deep breath.
Smile. Answer confidently. You will do great! 👍😊
Flowchart → Visual Thinking → Smart Solutions → Better
Results! 🚀
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