JEE Main Physical Chemistry — Electrochemistry & Kinetics: Chemical Kinetics – Chapter Test
JEE Main Physical Chemistry — Electrochemistry & Kinetics: Chemical Kinetics – Chapter Test is an online chapter test in the JEE Main pattern, covering Physical Chemistry — Electrochemistry & Kinetics. Attempt it on SeatBeat with a timer like the real exam, then see a detailed solution for every question and your score and weak-topic analysis.
Topics in this test
| Topic | Questions |
|---|---|
| Physical Chemistry — Electrochemistry & Kinetics | 20 |
Difficulty: 9 medium · 11 hard
Chemical Kinetics MCQ questions with answers
The first 3 of 20 questions. Unlock the series for the rest, each with a solution.
Q1. A first-order reaction is 50% complete in 20 minutes. The time required for it to become 75% complete is:
एक प्रथम-कोटि अभिक्रिया 20 मिनट में 50% पूर्ण होती है। इसके 75% पूर्ण होने के लिए अपेक्षित समय है:
- A. 40 min / 40 मिनट
- B. 30 min / 30 मिनट
- C. 60 min / 60 मिनट
- D. 80 min / 80 मिनट
Solution
For a first-order reaction 50% completion corresponds to one half-life (20 min) and 75% completion corresponds to two half-lives, i.e. 40 min.
प्रथम-कोटि अभिक्रिया के लिए 50% पूर्णता एक अर्ध-आयु (20 min) के संगत है और 75% पूर्णता दो अर्ध-आयुओं के संगत है, अर्थात् 40 min।
Q2. Assertion (A): For a first-order reaction, the half-life is independent of the initial concentration of the reactant. Reason (R): For a first-order reaction, t½ = 0.693/k, which contains no concentration term. Select the correct option:
अभिकथन (A): किसी प्रथम-कोटि अभिक्रिया के लिए, अर्ध-आयु अभिकारक की प्रारंभिक सांद्रता से स्वतंत्र होती है। कारण (R): किसी प्रथम-कोटि अभिक्रिया के लिए, t½ = 0.693/k, जिसमें कोई सांद्रता पद नहीं होता। सही विकल्प चुनें:
- A. Both A and R are true but R is not the correct explanation of A / A तथा R दोनों सत्य हैं परंतु R, A की सही व्याख्या नहीं है
- B. Both A and R are true and R is the correct explanation of A / A तथा R दोनों सत्य हैं तथा R, A की सही व्याख्या है
- C. A is false but R is true / A असत्य है परंतु R सत्य है
- D. A is true but R is false / A सत्य है परंतु R असत्य है
Solution
Both statements are true, and the expression t½ = 0.693/k (independent of [A]₀) is precisely why the half-life does not depend on initial concentration, so R correctly explains A.
दोनों कथन सत्य हैं, और व्यंजक t½ = 0.693/k ([A]₀ से स्वतंत्र) ही ठीक वह कारण है कि अर्ध-आयु प्रारंभिक सांद्रता पर निर्भर नहीं करती, अतः R, A की सही व्याख्या करता है।
Q3. A first-order reaction is allowed to proceed for a duration equal to four half-lives. The percentage of the reactant that has been consumed at the end of this period is:
एक प्रथम कोटि की अभिक्रिया को चार अर्ध-आयुओं के बराबर अवधि तक चलने दिया जाता है। इस अवधि के अंत में उपभुक्त हुए अभिकारक का प्रतिशत है:
- A. 93.75%
- B. 75.00%
- C. 87.50%
- D. 96.875%
Solution
After each half-life the amount of reactant halves, so after four half-lives the fraction remaining is (1/2)⁴ = 1/16 = 6.25%, meaning 93.75% has been consumed.
प्रत्येक अर्ध-आयु के बाद अभिकारक की मात्रा आधी हो जाती है, अतः चार अर्ध-आयुओं के बाद शेष अंश (1/2)⁴ = 1/16 = 6.25% होता है, अर्थात 93.75% उपभुक्त हो चुका है।
Frequently asked questions
How many questions are in the JEE Main Physical Chemistry — Electrochemistry & Kinetics: Chemical Kinetics – Chapter Test?
20 questions for 20 marks, to be answered in 20 minutes.
Is there negative marking in the JEE Main Physical Chemistry — Electrochemistry & Kinetics: Chemical Kinetics – Chapter Test?
Yes — 0.25 marks are deducted for each wrong answer, as in the real exam pattern.
Which topics does the JEE Main Physical Chemistry — Electrochemistry & Kinetics: Chemical Kinetics – Chapter Test cover?
Physical Chemistry — Electrochemistry & Kinetics (20 questions).
Is the JEE Main Physical Chemistry — Electrochemistry & Kinetics: Chemical Kinetics – Chapter Test free?
It is part of the JEE Main 2027 Mock Test Series (104 tests, ₹299). You can first try Basic Concepts & Atomic Structure – Topic Test for free.
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