UPSC CS Main 2021 Chemistry Paper-II Question Paper PDF

Central Government Jobs Other Jobs 2021

  • Year 2021
  • Conducted By UPSC
  • Questions 8
  • Maximum Marks 250
  • Duration Three Hours
  • Languages Hindi & English

Exam Details

Detail Information
Examination UPSC CS (Main) Exam
Year 2021
Conducting Body UPSC
Paper Chemistry Paper-II
Subject Chemistry
Duration Three Hours
Maximum Marks 250
Number of Questions 8
Question Type Mixed

This is the official question paper for the UPSC Civil Services (Main) Examination 2021, specifically for Chemistry Paper-II. The paper is designed to test candidates' in-depth knowledge of chemistry, carrying a maximum of 250 marks and a duration of three hours. It comprises eight questions divided into two sections, with candidates required to answer five questions in total, including compulsory questions 1 and 5, and at least one from each section. This paper is a crucial resource for aspirants preparing for the UPSC Civil Services Main examination, offering insights into the exam's structure, difficulty level, and the types of questions asked.

Major Topics Covered

  • Chemical Reactions
  • Isotopic Labeling
  • Quaternary Ammonium Salts
  • Sodium Amide Reactions
  • Reaction Mechanisms
  • Nucleophilic Reactivity
  • Benzaldehyde Derivatives
  • Lewis Acids

Why This Paper is Important

  • Useful for UPSC CS (Main) Exam preparation
  • Helps understand the latest exam pattern
  • Useful for practice and self-assessment
  • Covers frequently asked General Studies topics
  • Helpful for analysing question trends

Related Resources

  • UPSC CS (Main) Exam 2021 Chemistry Paper-I
  • UPSC CS (Main) Exam 2020 Chemistry Paper-II
  • UPSC CS (Main) Exam 2021 General Studies Paper-I
  • UPSC CS (Main) Exam 2021 Chemistry Paper-II Answer Key
  • UPSC CS (Main) Exam Chemistry Syllabus
  • UPSC CSE Syllabus
  • UPSC CS (Main) Exam Pattern
  • UPSC CSE Exam Pattern

Instructions

  • पुस्तिका के मुखपृष्ठ पर अंकित निर्दिष्ट स्थान पर किया जाना चाहिए।
  • प्राधिकृत माध्यम के अतिरिक्त अन्य किसी माध्यम में लिखे गए उत्तर पर कोई अंक नहीं मिलेंगे ।
  • जहाँ आवश्यक हो, निर्देशांक आरेखों को प्रश्न का उत्तर देने के लिए दिए गए स्थान में ही बनाना है।
  • जब तक उल्लिखित न हो, संकेत तथा शब्दावली प्रचलित मानक अर्थों में प्रयुक्त हैं।
  • यदि आवश्यक हो, तो उपयुक्त आँकड़ों का चयन कीजिए तथा उनको निर्दिष्ट कीजिए ।
  • प्रश्नों के उत्तरों की गणना क्रमानुसार की जाएगी।
  • आंशिक रूप से दिए गए प्रश्नों के उत्तर को भी मान्यता दी जाएगी यदि उसे काटा न गया हो।
  • प्रश्न-सह-उत्तर पुस्तिका में खाली छोड़े गए कोई पृष्ठ अथवा पृष्ठ के भाग को पूर्णतः काट दीजिए ।

  • There are EIGHT questions divided in TWO SECTIONS and printed both in HINDI and in ENGLISH.
  • Candidate has to attempt FIVE questions in all.
  • Question Nos. 1 and 5 are compulsory and out of the remaining, THREE are to be attempted choosing at least ONE question from each Section.
  • The number of marks carried by a question/part is indicated against it.
  • Answers must be written in the medium authorized in the Admission Certificate which must be stated clearly on the cover of this Question-cum-Answer (QCA) Booklet in the space provided.
  • No marks will be given for answers written in a medium other than the authorized one.
  • Coordinate diagrams, wherever required, shall be drawn in the space provided for answering the question itself.
  • Unless otherwise mentioned, symbols and notations have their usual standard meanings.
  • Assume suitable data, if considered necessary, and indicate the same clearly.
  • Attempts of questions shall be counted in sequential order.
  • Unless struck off, attempt of a question shall be counted even if attempted partly.
  • Any page or portion of the page left blank in the Question-cum-Answer Booklet must be clearly struck off.

Questions (page 2)

Section A

Q1.

(a) इस अभिक्रिया में
R - COO- + Br - CN longrightarrow R - CN + Br- + CO2
सायनाइड (–CN) समूह उत्पाद में कहां से उत्पन्न होता है ? समस्थानिक लेबलिंग प्रविधि के प्रयोग द्वारा स्पष्ट करें।
In the reaction
R - COO- + Br - CN longrightarrow R - CN + Br- + CO2
What is the origin of - CN group in the product? Explain by using isotopic labelling technique.

(b) निम्नलिखित चतुष्क अमोनियम लवण को जब सोडियम ऐमाइड के साथ निम्न तापमान और उच्च तापमान पर अभिक्रियत करते हैं तो उत्पादों के बनने का विवरण दें।
overrightarrowCH3_3 overrightarrowN-CH2-C6H5
X-
Discuss the product(s) formation when above quaternary ammonium salt is treated with sodium amide at low temperature and at high temperature.

(c) निम्नलिखित अभिक्रिया के उत्पाद A और B लिखें। उनके बनने की क्रियाविधि भी दें। इनमें से कौन सा मुख्य उत्पाद है और क्यों ?
mathitOH BF3: OE12
A + B
Write the products A and B in the above reaction. Also give the mechanism of their formation. Which one of these is the major product and why?

(d) निम्नलिखित यौगिकों की नाभिकस्नेही के प्रति BF3 : OE2 की उपस्थिति में अभिक्रियता की विवेचना कीजिये:
(i) पैरा(p)-ट्राईफ्लुओरोमेथिल बेन्जैल्डिहाइड
(ii) पैरा(p)-टॉलूऐल्डिहाइड
Discuss the reactivity of following compounds towards nucleophile in the presence of BF3 : OE2:
(i) p-trifluoromethyl benzaldehyde
(ii) p-tolualdehyde

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Frequently asked questions

What is the name of the exam for which this paper is intended?

This question paper is for the UPSC CS (Main) Exam.

What is the subject and paper code of this question paper?

The subject is Chemistry, and the paper is Paper-II with the code HXS-B-CHM.

In which year was this UPSC CS (Main) exam conducted?

The exam was conducted in the year 2021.

Who is the conducting body for this examination?

The examination is conducted by UPSC (Union Public Service Commission).

What is the maximum marks for Chemistry Paper-II?

The maximum marks for Chemistry Paper-II is 250.

What is the time allowed to complete the Chemistry Paper-II?

The time allowed to complete the paper is three hours.

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