QUESTION PAPER
2022 BOARD EXAM
CBSE CLASS 12-PCM CHEMISTRY Board Paper 2022 — Set 1
2022
CHEMISTRY
CLASS 12-PCM
CBSE EXAMINATION PAPER-2022
CHEMISTRY
(Solved)
General Instructions :
Read the following instructions carefully and follow them :
- This question paper contains 6 questions. All questions are compulsory.
- This question paper is divided into 3 sections.
- Section A – questions number 1 to 1 are case based questions
- Section B – questions number 2 to 2 are short answer
- Section C – questions number 3 to 6 are long answer
- There is no overall choice given in the question paper. However, an internal choice has been provided in few questions.
- Use of calculator is NOT allowed.
Section A
Question 1.
Aldehydes, ketones and carboxylic acids are some of the important classes of organic compounds containing the carbonyl group. These are highly polar molecules due to the higher electronegativity of oxygen relative to carbon in the carbonyl group. Aldehydes are prepared by dehydrogenation or controlled oxidation of primary alcohols and controlled reduction of acyl halides. Ketones are prepared by oxidation of secondary alcohols and hydration of alkynes. Aldehydes and ketones undergo nucleophilic addition reactions onto the carbonyl group but carboxylic acids do not undergo nucleophilic addition reaction. The alpha (α) - hydrogens of aldehydes and ketones are acidic. Therefore, aldehydes and ketones having at least one α-hydrogen undergo Aldol condensation.
Section B
Question 2.
[2 Marks]
Define rate of reaction. Write two factors that affect the rate of reaction.
Section C
Question 3.
[3 Marks]
A first order reaction is 50% complete in 40 minutes. Calculate the time required for the completion of 90% of reaction.
[Given: log 20.3010, log 10=1]
Question 4.
[3 Marks]
Write the structures of A, B and C in the following reactions:
Question 5.
[3 Marks]
Define transition elements. Which of the d-block elements may not be regarded as the transition elements ? Why transition metals generally form coloured compounds?
Question 6.
[3 Marks]
Write any three differences between physisorption and chemisorption..
Other Years — CHEMISTRY