CBSE: CBSE Class 12 Chemistry Marking Scheme 2021 along with CBSE Class 12 Chemistry Sample Paper 2021 is available here for download in PDF format. Students preparing for CBSE Class 12th Chemistry Board Exam 2021 are suggested to download these resources & take a close look to check the new exam pattern, marking scheme and the difficulty level of the exam.
Also Check: CBSE Date Sheet 2021 for 10th & 12th Board Exams
CBSE Class 12 Chemistry Marking Scheme 2021:
SECTION - A (OBJECTIVE TYPE)
1. Read the passage given below and answer the following questions:
An efficient, aerobic catalytic system for the transformation of alcohols into carbonyl compounds under mild conditions, copper-based catalyst has been discovered. This copper-based catalytic system utilizes oxygen or air as the ultimate, stoichiometric oxidant, producing water as the only by-product
A wide range of primary, secondary, allylic, and benzylic alcohols can be smoothly oxidized to the corresponding aldehydes or ketones in good to excellent yields. Air can be conveniently used instead of oxygen without affecting the efficiency of the process. However, the use of air requires slightly longer reaction times. This process is not only economically viable and applicable to large-scale reactions, but it is also environmentally friendly.
The following questions are multiple choice questions. Choose the most appropriate answer:
(i)The Copper based catalyst mention in the study above can be used to convert:
(a) propanol to propanoic acid
(b) propanone to propanoic acid
(c) propanone to propan-2-ol
(d) propan-2-ol to propanone
(ii) The carbonyl compound formed when ethanol gets oxidised using this copper-based catalyst can also be obtained by ozonolysis of:
Which of the following is a secondary allylic alcohol?
(iii) Benzyl alcohol on treatment with this copper-based catalyst gives a compound ‘A’ which on reaction with KOH gives compounds ‘B’ and ‘C’. Compound ‘B’ on oxidation with KMnO4- KOH gives compound ‘C’. Compounds ‘A’, ‘B’ and ‘C’ respectively are :
(a) Benzaldehyde, Benzyl alcohol, potassium salt of Benzoic acid
(b) Benzaldehyde, potassium salt of Benzoic acid, Benzyl alcohol
(c) Benzaldehyde, Benzoic acid, Benzyl alcohol
(d) Benzoic acid, Benzyl alcohol, Benzaldehyde
(iv) An organic compound ‘X’ with molecular formula C3H8O on reaction with this copper based catalyst gives compound ‘Y’ which reduces Tollen’s reagent. ‘X’ on reaction with sodium metal gives ‘Z’ . What is the product of reaction of ‘Z’ with 2- chloro-2-methylpropane?
For the rest of the questions and answers, download CBSE Class 12 Chemistry Marking Scheme 2021 & CBSE Class 12 Chemistry Marking Scheme 2021 from the following links