BTechibtechi.in
Loading Loading
Free IIT Madras BS notes, PYQs and mock tests at btechi.in

MAD II · Promises, async/await & event loop

19 questions · 59.5 marks · 5 papers

Answer key

Indian Institute of Technology Madras

BS Degree Programme · Examination & Study Paper

Modern Application Development II

Promises, async/await & event loop

Official Paper

Examination Instructions & Guidelines

Solve on notebook/paper first before checking solutions.
MCQ: Exactly 1 option is correct. Negative marking applies.
Scientific calculator allowed for all calculations.
Official answer key is sealed at the end of this sheet.

End Term · 31 Aug 2025 (FN)End Term

Q1MCQ3 Marks·Choose one option
Asked 5 times Key ↓
1. AR P Q S
2. BP R S Q
3. CR P S Q
4. DR S P Q
Q2MCQ3 Marks·Choose one option
Key ↓
1. A
2. B
3. C
4. D
Q3MCQ4.5 Marks·Choose one option
Asked 5 times Key ↓
1. A
2. B
3. C
4. D
Q4MCQ4.5 Marks·Choose one option
Asked 4 times Key ↓
1. A
2. B
3. C
4. D
Q5MCQ4.5 Marks·Choose one option
Key ↓
1. AResult: null
2. BError: HTTP 404, Result: null
3. CError: HTTP 404
4. DUnhandled promise rejection

End Term · 31 Aug 2025 (AN)End Term

Q6MCQ3 Marks·Choose one option
Asked 5 times Key ↓
1. AR P Q S
2. BP R S Q
3. CR S P Q
4. DR P S Q
Q7MCQ3 Marks·Choose one option
Asked 4 times Key ↓
Consider the following javascript program. What will be the output of the above program on the browser’s console?
1. A
2. B
3. C
4. D
Read the passage below, then answer Q8–Q9
Prashant and Nikita are creating a quiz question paper collaboratively. They are each working on different sections — and complete their tasks in parallel. Meanwhile, Mayur is enjoying a single- player game that finishes when the game loop ends.
To compare productivity:
● If Prashant and Nikita (together) finish faster than Mayur, the winner is "Team".
● If Mayur finishes faster, he wins.
● If both take the same time, Mayur wins by default.
You are simulating this scenario in the browser.Prashant and Nikita are represented using parallel Promises. Mayur is represented using a single Promise. The frontend must calculate who finishes first using asynchronous logic, and display the result.
Based on the above data, answer the given subquestions.
Q8MCQ3 Marks·Choose one option
Key ↓
If Prashant and Nikita finish together in 3 seconds (since Promise.all waits for both), and Mayur finishes in 4 seconds, who wins?
1. AMayur
2. BTeam
3. CNikita
4. DRace condition prevents output
Q9MCQ3 Marks·Choose one option
Key ↓
The Team takes 5 seconds in total. Mayur takes 2 seconds. According to the logic of app2.js, who is the winner?
1. AMayur
2. BTeam
3. CNikita
4. DError due to async logic

Quiz 2 · 3 Aug 2025 (AN)Quiz 2

Q10MCQ3 Marks·Choose one option
Key ↓
1. ATotal Score: 80
2. BTotal Score: 90
3. CTotal Score: 120
4. DTotal Score: NaN
Q11MCQ3 Marks·Choose one option
Key ↓
1. A
2. B
3. C
4. D
5. E

End Term · 22 Dec 2024 (FN)End Term

Q12MCQ3 Marks·Choose one option
Asked 2 times Key ↓
1. AStart Inside Timeout Inside Promise End
2. BStart Inside Promise Inside Timeout End
3. CStart End Inside Timeout Inside Promise
4. DStart End Inside Promise Inside Timeout
Q13MCQ3 Marks·Choose one option
Asked 4 times Key ↓
What will be the output on the console?
1. Aerror4
2. B7
3. Cerror
4. Dundefined
Q14MCQ3 Marks·Choose one option
Asked 5 times Key ↓
1. ABegin, Start, 5, End, Finish
2. BBegin, Finish, Start, 5, End
3. CBegin, Finish, Start, End, 5
4. DBegin, Start, Finish, 5, End
Q15MCQ2 Marks·Choose one option
Asked 2 times Key ↓
Which of the following statements is false when using the “async” and “await” keywords in JavaScript?
1. AThe “await” keyword can only be used inside an async function.
2. BThe “await” keyword pauses the execution of the surrounding async function until the promise resolves.
3. CThe async functions always return a promise, even if the return value is not a promise.
4. DThe async functions run synchronously, but their await statements execute asynchronously.

End Term · 22 Dec 2024 (AN)End Term

Q16MCQ3 Marks·Choose one option
Asked 4 times Key ↓
What will be the output on the console?
1. A7
2. Berror
3. Cundefined
4. Derror4
Q17MCQ3 Marks·Choose one option
Asked 5 times Key ↓
1. ABegin, Start, 5, End, Finish
2. BBegin, Start, Finish, 5, End
3. CBegin, Finish, Start, 5, End
4. DBegin, Finish, Start, End, 5
Q18MCQ3 Marks·Choose one option
Asked 2 times Key ↓
1. A
2. B
3. C
4. D
Q19MCQ2 Marks·Choose one option
Asked 2 times Key ↓
Which of the following statements is false when using the “async” and “await” keywords in JavaScript?
1. AThe “await” keyword can only be used inside an async function.
2. BThe async functions run synchronously, but their await statements execute asynchronously.
3. CThe “await” keyword pauses the execution of the surrounding async function until the promise resolves.
4. DThe async functions always return a promise, even if the return value is not a promise.

Official Key

Master Answer Key & Explanations

Official answer keys from IIT Madras BS past papers. Click any question to review.

Reveal Key

Q1C

Q2A

Q3B

Q4A

Q5B

Q6D

Q7B

Q8B

Q9A

Q10B

Q11B

Q12D

Q13A

Q14D

Q15D

Q16D

Q17B

Q18B

Q19B

Questions and answer keys are reproduced from the official IIT Madras BS papers. Topics and repeated question types are BTechi’s own grouping. BTechi is not affiliated with IIT Madras.