CBSE Class 12 Chemistry Previous Year Question Paper 2020 (Delhi Set 1)
This is the CBSE Class 12 Chemistry Previous Year Question Paper from the 2020 Main Exams for Delhi Set 1. The question paper comprises four sections: A, B, C, and D, with a total of 37 compulsory questions. Section A includes 20 very short answer type questions, each carrying one mark. Section B features 7 short answer type questions, each worth two marks. Section C contains 7 long answer type-I questions, each carrying three marks. Section D consists of 3 long answer type-II questions, each worth five marks. While there is no overall choice, internal choices are provided in some questions across sections B, C, and D. This board question paper is an invaluable resource for students preparing for their Class 12 Chemistry board exams, offering a realistic assessment of the exam format and difficulty level.
Quick info
| Board | CBSE |
|---|---|
| Class | 12 |
| Subject | Chemistry |
| Session | 2020 |
| Language | English |
| Type | Previous Year Question Paper |
| Exam type | Board Exam |
Paper pattern
The question paper comprises four sections (A, B, C, D) with 37 questions in total. Section A has 20 one-mark questions, Section B has 7 two-mark questions, Section C has 7 three-mark questions, and Section D has 3 five-mark questions. Internal choices are provided in some questions.
Topics covered
Paper topics
- Halogens
- Electron Gain Enthalpy
- Fluorine Anomalous Behaviour
- Hydrogen Halides
- Inter-halogens
Important topics
- Anomalous behaviour of Fluorine
- Electron gain enthalpy of halogens
- Reducing character of hydrogen halides
PDF preview
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Question paper text
Chemistry Delhi (Set 1)
General Instructions:
Read the following instructions very carefully and strictly follow them:
- Question paper comprises four sections - A, B, C and D.
- There are 37 questions in the questions paper. All questions are compulsory.
- Section - A: Q. No. 1 to 20 are very short answer type questions carrying one mark each. Answer these questions in one word or one sentence.
- Section - B: Q. No. 21 to 27 are short answer type questions carrying two marks each.
- Section - C: Q. No. 28 to 34 are long answer type-I questions carrying three marks each.
- Section - D: Q. No. 35 to 37 are long answer type-II questions carrying five marks each.
- There is NO overall choice in the question paper. However an internal choice has
been provided in 2 questions of two marks, 2 questions of three marks and all the 3 questions of five marks. You have to attempt only one of the choices in such questions.
- However, separate instructions are given with each section and question, wherever necessary.
- Use of calculators and log tables is NOT permitted.
Read the given passage and answer the question follow:
The halogens have the smallest atomic radii in their respective periods. The atomic radius of fluorine is extremely small. All halogens exhibit – 1 oxidation state. They are strong oxidising agents and have maximum negative electron gain enthalpy. Among halogens, fluroine shows anomalous behaviour in many properties.
For example electro negativity and ionisation enthalpy are higher for fluorine than expected whereas bond dissociation enthalpy, m.p and b.p and electron gain enthalpy are quite lower than expected. Halogens react with hydrogen to give hydrogen halides (HX) and combine amongst themselves to form a number of compounds of the type XX', XX'<sub>3</sub>, XX'<sub>5</sub> and XX'<sub>7</sub> called inter-halogens.
Question 1
Why halogens have maximum negative electron gain enthalpy?
Solution:
Due to the smallest size of halogens in their respective periods, the value of Zeff is maximum hence the negative value of electron gain enthalpy is maximum.
Read the given passage and answer the question follow:
The halogens have the smallest atomic radii in their respective periods. The atomic radius of fluorine is extremely small. All halogens exhibit – 1 oxidation state. They are strong oxidising agents and have maximum negative electron gain enthalpy. Among halogens, fluroine shows anomalous behaviour in many properties.
For example electro negativity and ionisation enthalpy are higher for fluorine than expected whereas bond dissociation enthalpy, m.p and b.p and electron gain enthalpy are quite lower than expected. Halogens react with hydrogen to give hydrogen halides (HX) and combine amongst themselves to form a number of compounds of the type XX', XX'<sub>3</sub>, XX'<sub>5</sub> and XX'<sub>7</sub> called inter-halogens.
Question 2
Why fluorine shows anomalous behaviour as compared to other halogens?
Solution:
Fluorine shows abnormal behavior due to its very small size.
Read the given passage and answer the question follow:
The halogens have the smallest atomic radii in their respective periods. The atomic radius of fluorine is extremely small. All halogens exhibit - 1 oxidation state. They are strong oxidising agents and have maximum negative electron gain enthalpy. Among halogens, fluroine shows anomalous behaviour in many properties.
For example electro negativity and ionisation enthalpy are higher for fluorine than expected whereas bond dissociation enthalpy, m.p and b.p and electron gain enthalpy are quite lower than expected. Halogens react with hydrogen to give hydrogen halides (HX) and combine amongst themselves to form a number of compounds of the type XX', XX'<sub>3</sub>, XX'<sub>5</sub> and XX'<sub>7</sub> called inter-halogens.
Question 3
Arrange the hydrogen halides (HF to HI) in the decreasing order of their reducing character.
Frequently asked questions
What is this document?
This is the CBSE Class 12 Chemistry Previous Year Question Paper from the 2020 Main Exams, Delhi Set 1, for board exam practice.
What is the structure of the Chemistry 2020 paper?
The paper has four sections (A, B, C, D) with 37 questions. Section A has 20 one-mark questions, Section B has 7 two-mark questions, Section C has 7 three-mark questions, and Section D has 3 five-mark questions.
Are there any choices in the questions?
Yes, there is no overall choice, but internal choices are provided in 2 questions of two marks, 2 questions of three marks, and all 3 questions of five marks.
How can solving this previous year paper help?
Solving this previous year question paper helps students understand the CBSE exam pattern, question types, and difficulty level, thereby improving their preparation and confidence for the board exams.
What topics are covered in this paper?
This paper covers topics such as halogens, electron gain enthalpy, anomalous behaviour of fluorine, hydrogen halides, and inter-halogens, among others.
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