Class 12 Chemistry Answer Key 2023, Question Paper All Sets PDF

Class 12 Chemistry Answer key 2023

Class 12 Chemistry Answer Key: The Central Board of Secondary Education is all set to conduct the CBSE Class 12 Chemistry Exam 2023 on 28 February 2023. We will cover the CBSE Class 12 Chemistry Answer Key 2023 on this page in detail.  The chemistry exam will conclude at 01:30 pm, after completion of the examination we will update the CBSE Class 12 Chemistry Answer Key 2023 on this page. The students appearing in the examination can match their answers with the unofficial CBSE Class 12 Chemistry Answer Key 2023 prepared by the expert facilities of Adda247. 

Answer Key Class 12 Chemistry 2023

CBSE Class 12 Chemistry Answer Key 2023 given on this page is error-free and all the answers to CBSE Class 12 Chemistry Answer Key 2023 are framed by the faculties who have years of experience in teaching Class 12 Chemistry. Below we have given the highlights of CBSE Class 12 Answer Key Chemistry. The students must check the brief information of CBSE Class 12 Chemistry Answer Key 2023 provided in the table below: 

CBSE Class 12 Chemistry Additional Practice Questions 2023

Class 12 Chemistry Exam Answer key Analysis 2023

Here we have given the complete CBSE Class 12 Chemistry Exam Analysis 2023. In CBSE Class 12 Chemistry Answer key & Exam Analysis 2023, we will cover the difficulty level of the exam, out-of-syllabus questions, and mistakes in the question paper. After completion of the CBSE Chemistry Exam, the students must match their responses with the Chemistry Answer Key provided on this page and must check the CBSE Class 12 Chemistry Exam Analysis 2023.

Class 12 Chemistry Answer Key 2023 Overview

CBSE Class 12 Chemistry Answer Key 2023: Exam Pattern 

With calculating the scores with the Class 12 Chemistry Answer Key 2023, students must know the Chemistry marking Scheme of Each section.  As per the CBSE Class 12 Chemistry sample paper, the CBSE Class 12 Chemistry question paper consists o Five sections. All the sections hold different marks and different types of questions. The board will ask the very short answer type, short answer type, and case-based questions in the CBSE Class 12 Chemistry Examination. Check out the detailed section-wise pattern listed below: 

1. Section A consists of 18 Questions carrying 1 mark each [Multiple Choice Questions]

2. Section B consists of 7 questions carrying 2 marks each [Very Short Answer Questions]

3. Section C consists of 5 questions carrying 3 marks each [Short Answer Questions]

4. Section D consists of 2 Questions carrying 4 marks each [Case Based Questons]

5. Section E consists of 2 Questions carrying 5 marks each [Long Answer Questions]

Also Check: Class 12 Chemistry Previous Year Question Papers With Solutions

Class 12 Chemistry Answer Sheet 2023

Here we have provided the Class 12 Chemistry Answer Sheet 2023 for Chemistry question set 2 and 3. A majority of students said that Section A is Multiple Choice questions are a little bit tricky and they found some difficulties while solving these sections. Candidates can cross-check their answers with the Class 12 Chemistry Answer Key 2023 of Section A.

Class 12 Chemistry Answer Key 2023 of Section A

Chemistry Class 12 Answer key 2023-Student’s Reaction

CBSE Class 12 Chemistry Answer Key with Paper Solution 2023

Once the CBSE Class 12 Chemistry Exam 2023 will conclude, here we will provide the detailed 100% accurate CBSE Class 12 Chemistry Answer key 2023 with question paper analysis as soon as possible. Stay connected with us.

Class 12 Most Expected Chemistry Board Paper-Check Now

Class 12 Chemistry Question Papers 2023 Set 2

CBSE Class 12 Chemistry Question Papers 2023 Set 3

Answer Key Class 12 Chemistry Set 3

1, A compound CaCl2.6h2O undergoes complete dissociation in water,The Van’t Hoff Factor ‘i’ is:

a)  9, b) 6, c)3, d) . 4

Answer: c) 3

2. For a Zero order reaction of type A →products, the rate equation may be expressed as:

Answer: Option (a)

3. Which of the following Cu 2+ halide is not known?

(a) CuBr2

(b) Cul2

(c) CuCl2

(d) CuF2

Answer: Option (b)

Q4. Which of the following structures represents a-D-glucose?

Answer: (a)

5. The compounds [Cr(H2O)lCl3, [Cr(H2O) Cl]C12. H2O and [Cr(H2O)4C12]Cl. 2H2O exhibit:

(a) Linkage isomerism
(b) Geometrical isomerism
(c) . Ionization isomerism
(d) Hydrate isomerism

Answer: (d) Hydrate isomerism

6. Which of the following alkenes on acid catalysed hydration gives a tertiary alcohol?

(a) 2-Butene

(b) 2-Methylpropene

(c) Propene

(d) 95 1-Butene

Answer: (b) 2-Methylpropene

7. When nitrobenzene is heated with tin and concentrated HCl, the product formed is:

Answer: (a)

8. The reaction of 1-phenyl-2-chloropropane with alcoholic KOH gives mainly:

(a) 1-phenylpropene

(b) 3-phenylpropene

(c) 1-phenylpropene 1-phenylpropan-3-ol

(d) 1-phenylypropan-2-ol

Answer: (a) 1-phenylpropene

9. Corrosion of iron is:

(a) a decomposition process a photochemical process
(b) a photochemical process
(c) an electrochemical process
(d) a reduction process

Answer: (a) reduction process

10. The number of molecules that react with each other in an elementary reaction is a measure of the:

(a) activation energy of the reaction
(b) order of the reaction
(c) stoichiometry of the reaction
(d) molecularity of the reaction

Answer: (d) molecularity of the reaction

11. On hydrolysis, which of the following carbohydrates gives glucose and galactose?

(a) Sucrose
(c) Maltose
(b) Lactose
(d) Cellulose

Answer: (b) Lactose

12. The deficiency of which of the following vitamins causes ‘Rickets’?

(a) Vitamin A
(b) Vitamin D
(c) Vitamin B
(d) Vitamin C

Answer; (b) Vitamin D

13. Which of the following is an ‘Acetal’?

Answer: (d)

For Questions number 15 to 18, two statements are given – one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
(c) Assertion (A) is true, but Reason (R) is false.
(d) Assertion (A) is false, but Reason (R) is true.

15. Assertion (A): When NaCl is added to water, a depression in freezing point is observed.

Reason (R): The vapour pressure of solution is increased which causes depression in freezing point.

Answer:(c) Assertion (A) is true, but Reason (R) is false.

16. Assertion (A): Monobromination of aniline can be conveniently done by protecting the amino group by acetylation.

Reason (R): Acetylation decreases the activating effect of the amino group.

Answer:(c) Assertion (A) is true, but Reason (R) is false.

Class 12 Chemistry Answer Key 2023

Section- A

• The magnetic moment of [NiCl4]2-

(a) 1.82 BM
(b) 2.82 BM
(c) 4.42 BM
(d) 5.46 BM
(Atomic no : Ni= 28)
Answer: (a) 1.82 BM

• Which of the following cell was used in Apollo space programme?

(a) Mercury Cell

(b) Daniel Cell

(c) H2-O2 Fuel cell

(d) Dry Cell

Answer: (c) H2-O2 Fuel cell

• Which one of the following has lowest pKa value?

(a) CH3-COOH

(b) O2N-CH2-COOH

(c) Cl-CH2-COOH

(d) HCOOH

Answer: (b) O2N-CH2-COOH

• Which of the following ions has the electronic configuration 3d6 ?

(a) Ni³⁺
(b) Co³⁺
(c) Mn²⁺
(d) Mn³⁺
Answer: (b) CO³⁺

• Consider the following standard electrode potential values:

Fe3+ (aq) + e- —> Fe2+ (aq) Eo = + 0.77 V
MnO4- (aq) + 8H+ + 5e- —-> Mn2+ (aq) + 4H2O (l) Eo = + 1.51V
What is the cell potential for the redox reaction?
(a) -2.28 V
(b) – 0.74 V
(c) + 0.74 V
(d) + 2.28 V
Answer: (c)  +0.74 V

4. The following experimental rate data were obtained for a reaction carried out at 25o C:

A(g) + B(g) —-> C(g) + D(g)

• A voltaic cell is made by connecting two half cells represented by half equations below:

Sn2+(aq) + 2e- –>Sn(s)Eo=-0.14 V

Fe3+(aq)+e- –> Fe2+ (aq)Eo=+0.77 V

• Which statement is correct about this voltaic cell?

(a) Fe2+ is oxidised and the voltage of the cell is -0.91 V.
(b) Sn is oxidised and the voltage of the cell is 0.91 V.
(c) Fe2+ is oxidised and the voltage of the cell is 0.91 V.
(d) Sn is oxidised and the voltage of the cell is 0.63 V.

Answer: to be updated

• What are the orders with respect to A(g) and B(g)?

Answer: To be updated

• Which of the following aqueous solution will have highest boiling point?

(a) 1.0 M KCl

(b) 1.0 M K₂SO4

(c) 2.0 M KCl

(d) 2.0 M K2SO4

Answer: to be updated

• Amides can be converted into amines by the reaction named

(a) Hoffmann degradation

(b) Ammonolysis

(c) Carbylamine

(d) Diazotisation

Answer: (a) Hoffmann degradation

• Which of the following would not be a good choice for reducing nitrobenzene to aniline?

(a) LiAlH4

(b) H2/Ni

(c) Fe and HCl

(d) Sn and HCl

Answer: (a) LiAlH₄

• Which property of transition metals enables them to behave as catalysts?

(a) High melting point

(b) High ionisation enthalpy

(c) Alloy Formation

(d) Variable oxidation states

Answer: (d) Variable oxidation states

• Which of the following statements is not true about glucose?

(a) It is an aldohexose.

(b) On heating with HI it forms n-hexane.

(c) It is present in pyranose form.

(d) It gives 2,4 DNP test.

Answer: (d) It gives 2,4 DNP test.

• Which of the following alcohols will not undergo oxidation?

(a) Butanol

(b) Butan-2-ol

(c) 2-Methylbutan-2-ol

(d) 3-Methylbutan-2-ol

Answer: (d) 3-Methylbutan-2-ol

• Four half reactions I to IV are shown below:

1.  2Cl- —> Cl2 + 2e-
2. 4OH- —-> O2 + 2H2O + 2e-
3. Na+ + e- —-> Na
4. 2H+ + 2e- —-> H2

 Which two of these reactions are most likely to occur when concentrated brine is electrolysed?

(a) I and III

(b) I and IV

(c) II and III

(d) II and IV

For the questions 15 to 18 , two statements are given – one labeled as Assertion (A) and the other labelled as Reason (R ). Select the correct answer to these questions from the codes (a), (b), (c ), and (d) as given below:

(a) Both Assertion (A) and Reason (R ) are true and (R) is the correct explanation of the Assertion (A).
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
(c) Assertion (A) is true but Reason (R) is false.
(d) Assertion (A) is false, but Reason (R) is true.

15. Assertion (A) : Vitamin C cannot be stored in our body.

Reason (R) : Vitamin C is fat soluble and is excreted from the body in urine.
Answer: (c) Assertion (A) is true but Reason (R) is false

16. Assertion (A) : The half life of a reaction is the time in which the concentration of the reactant is reduced to one half of its initial concentration.

Reason (R) : In first order kinetics when concentration of reactant is doubled, its half life is doubled.

17. Assertion (A) : Bromination of benzoic acid gives m-bromobenzoic acid.

Reason (R) : Carboxyl group increases the electron density at the meta position.
Answer: (a) Both Assertion (A) and Reason (R ) are true and (R) is the correct explanation of the Assertion (A).

18. Assertion (A): EDTA is a hexadentate ligand.

Reason (R) : EDTA has 2 nitrogen and 4 oxygen donor atoms.
Answer: (a) Both Assertion (A) and Reason (R ) are true and (R) is the correct explanation of the Assertion (A).

CBSE Class 12 Chemistry Exam Paper Analysis 2023

We surveyed students to find out what they thought of the CBSE Class 12 Chemistry Paper Review 2023. The overall paper was simple to moderate. The questions were straightforward, and nothing was outside of the syllabus. There were some math problems that tested students’ analytical abilities, but everything else was typical in terms of complexity.

Section A, which consisted of MCQs, was the top-scoring component of the exam, according to our subject experts. For your convenience, the answer key for the Class 12 Chemistry test is provided in the sections below.

Class 12 Chemistry Question Papers 2023 Set 1 2 3 4 PDF Download

After Completion of the Exam, here we will provide the CBSE Class 12 Chemistry Question Papers 2023 Pdf. Candidates may download Class 12 Chemistry Question Papers and analyze the Class 12 Chemistry Answer key to calculate their expected scores.

Class 12 Chemistry Answer Key 2023 Previous Year Repeated Questions

Section A

Q.1: Arrange the following compounds in the increasing order of their property indicated.

i) Acetaldehyde, Benzaldehyde, Acetophenone, Acetone(Reactivity towards HCN)

Answer. Acetaldehyde<Acetone<Benzaldehyde<Acetophenone

iii) CH3CH2OH, CH3CHO, CH3COOH (Boiling point)

Answer.  CH3COOH<CH3CH2OH<CH3CHO

Q.2: In a plot of m against the square root of concentration (C12) for strong and weak electrolytes, the value of limiting molar conductivity of a weak electrolyte cannot be obtained graphically. Suggest a way to obtain this value. Also state the related law, if any.

Yes, we can do it by Kohlrausch’s law.

Kohlrausch’s law:  a statement in physical chemistry: the migration of an ion at infinite dilution is dependent on the nature of the solvent and on the potential gradient but not on the other ions present.

Q.3: Write reasons for the following statements : 

(i) Benzoic acid does not undergo Friedel-Crafts reaction.

No, benzoic acid does not undergo Friedel Craft reaction because the carboxylic group is deactivating and the Lewis acid catalyst and carboxylic group are bonded.

(ii) Oxidation of aldehydes is easier than that of ketones.

oxidation of aldenyde is easier than ketone due to presence of H-atoms linked to carbonyl group carbon which is absent in ketones.

Section B

Q.4: Write reasons for the following: 

(i) Ethylamine is soluble in water whereas aniline is insoluble. 

Ethylamine when added to water forms intermolecular H−bonds with water. Hence it is soluble in water. But aniline Can form H−bonding with water to a very small extent due to the presence of a large hydrophobic −C6H5 group. Hence aniline is insoluble in water.

(ii) Amino group is o- and p-directing in aromatic electrophilic substitution reactions, but aniline on nitration gives a substantial amount of m-nitroaniline. 

Nitration is carried out in an acidic medium. In an acidic medium, aniline is protonated to give anilinium ion (which is meta-directing).

For this reason, aniline on nitration gives a substantial amount of m-nitroaniline.

(iii) Amines behave as nucleophiles.

A nucleophile is a substance that is attracted to, and then attacks, a positive or slightly positive part of another molecule or ion. All amines contain an active lone pair of electrons on the very electronegative nitrogen atom. It is these electrons that are attracted to positive parts of other molecules or ions.

OR 

b) How will you carry out the following conversions:

i) Nitrobenzene to Aniline 

Nitrobenzene is reduced to aniline by Sn and concentrated HCl. Instead of Sn, Zn or Fe also can be used. Aniline salt is given from this reaction. Then aqueous NaOH is added to the aniline salt to get released aniline. This reaction is called nitrobenzene reduction.

• Benzene is a clear, colourless, highly flammable and volatile, liquid compound.
• Aniline is a yellowish to brownish oily liquid with a musty fishy odour organic compound.

ii) Ethanamide to Methanamine

React ethanamine with nitrous acid to form an azo compound, which further reacts with water to form ethanol, which on oxidising gives ethanoic acid. After treating with an excess of ammonia the ethanoic acid becomes ethanamide, which on further reacting with Bomine and a strong base (Hoffmann bromamide degradation reaction) to form methenamine.

iii) Ethanenitrile to Ethanamine 

it’s simple
reduction of nitriles with lithium aluminium hydride or catalytic hydrogenation produce primary amines. the reaction is

CH3C≡N + H2/Ni OR LiAlH4 →  CH3CH2NH2

Q.5(a)(i) Write the electronic configuration of d5 on the basis of crystal field splitting theory if Δ0 < P.

When Δo < P, it is weak field and high spin situation’. As a result one electron entered in eg orbital and 3 electrons in t2g.

(ii) [Fe(CN)6]³- is weakly paramagnetic whereas [Fe(CN)6]4- is diamagnetic. Give reason to support this statement [Atomic no. Fe = 26].

In both and , Fe exists in the +3 oxidation state i.e., in d⁵ configuration.

Since CN⁻ is a strong field ligand, it causes the pairing of unpaired electrons. Therefore, there is only one unpaired electron left in the d-orbital.

Therefore,

On the other hand, H₂O is a weak field ligand. Therefore, it cannot cause the pairing of electrons. This means that the number of unpaired electrons is 5.

Therefore,

Thus, it is evident that is strongly paramagnetic, while is weakly paramagnetic.

(iii) Write the number of ions produced from the complex [Co(NH3)6]C12 in solution. 

The given complex can be written as [Co(NH3)6]Cl2. Thus, [Co(NH3)6]+ along with two Cl− ions are produced.

OR

Q.(b)(i) Calculate the spin only magnetic moment of the complex [CoF613-. (Atomic no. of Co = 27)

Given ion is M2+ with the atomic no. 27.

So, electronic configuration of M2+ is  [Ar] 3d74s0

[Ar]  $\upharpoonleft$$\downharpoonright$   $\upharpoonleft$ $\downharpoonright$  $\upharpoonleft$   $\upharpoonleft$   $\upharpoonleft$

              3d                               4s

No. of unpaired e− s =3

So, the spin only magnetic moment is given by,

$\mu$=n(n+2)​       =3(3+2)​  =3X5​ =15​ BM

=3.87 BM

(ii) Write the IUPAC name of the given complex: [CrCl2(H20)4]Cl

The correct I.U.P.A.C. name for [CrCl2​(H2​O)4​]NO3​ complex is tetraaquadichlorochromium(III) nitrate.

Q.6 (i) Which ion amongst the following is colourless and why?

Ti4+, Cr3+, V3+

(Atomic number of Ti = 22, Cr = 24, V = 23)

Ti is colourless because it is having no unpaired e−e- for excitation to higher energy level and it is colourless.

(ii) Why is Mn²+ much more resistant than Fe²+ towards oxidation?

Mn2+ is much more resistant than Fe2+ towards oxidationAs Mn2+ has stable configuration hence it is resistant towards oxidation. while in Fe2+ electronic configuration is 3d6 so it can lose one electron to give stable configuration 3d5.

(iii) Highest oxidation state of a metal is shown in its oxide or fluoride only. Justify the statement.

The highest oxidation state of a metal is exhibited in its oxide or fluoride only. This is because fluorine (F) and oxygen (O)are the most electronegative elements and the highest oxidation state shown by any transition element is +8.

Q.7 A compound ‘A’ (C2H4O) on oxidation gives ‘B’ (C2H4O2). ‘A’ undergoes an Iodoform reaction to give yellow precipitate and reacts with HCN to form the compound ‘C’. ‘C’ on hydrolysis gives 2-hydroxypropanoic acid. Identify the compounds ‘A’, ‘B’ and ‘C’. Write down equations for the reactions involved. 

Q.9(a) Write equations involved in the following reactions :

(i) Ethanamine reacts with acetyl chloride.

(ii) Aniline reacts with bromine water at room temperature. 

(iii) Aniline reacts with chloroform and ethanolic potassium hydroxide.

When aniline reacts with chloroform and alcoholic $KOH$ it gives an offensive smelling liquid i.e., phenyl isocyanide as product. It is called as isocyanide test. It is given by aliphatic and aromatic primary amines.

Q.9 (b)  (i) Write the IUPAC name for the following organic compound:  (CH3CH2)2NCH3

(CH3​CH2​)2​NCH3​ it is a tertiary amine, and the parent chain is ethanamine. IUPAC name is N – Ethyl – N- methyl ethanamine.

(ii) Write the equations for the following: 

(I) Gabriel phthalimide synthesis

Gabriel Phthalimide Synthesis Mechanism has 3 steps. The Synthesis is used to get primary amines from primary alkyl halides and is named after the German scientist Siegmund Gabriel.

The reaction has been generalized for applications in the alkylation of sulfonamides and imides & their deprotection in order to obtain amines. Alkylation of ammonia is quite inefficient, therefore it is substituted with phthalimide anion in the Gabriel synthesis.

(II) Hoffmann bromamide degradation 

When an amide is treated with bromine in an aqueous or ethanolic solution of sodium hydroxide, degradation of amide takes place leading to the formation of primary amine. This reaction involving degradation of amide and is popularly known as Hoffmann bromamide degradation reaction. The primary amine thus formed contains one carbon less than the number of carbon atoms in that amide.

RCONH₂ +Br₂ + 4NaOH

R-NH₂ + Na₂CO₃ + 2NaBr + 2H₂O

Q.11(a) i) Silver atom has completely filled d-orbitals in its ground state, it is still considered to be a transition element. Justify the statement. 

Silver (Ag) belongs to group 11 of d-block and its ground state electronic configuration is 4d10 5s1. It shows an oxidation state of +2 in its compounds like AgO and AgF2 in which its electronic configuration is d9 so it is a transition element.

ii) Why are E° values of Mn and Zn more negative than expected? 

Negative E° values of Mn2+ and Zn2+ are because of the stabilities of half-filled (3d5 : Mn2+)and fullyfilled (3d10 : Zn2+) configuration respectively. Ni2+ ion has higher E°  value due to highest negative enthalpy of hydration.

iii) Why do transition metals form alloys?

Transition metals have very similar atomic sizes. One metal can easily replace the other metal from its lattice to form solid solution (alloy). Transition metals are miscible with one another in the molten state. The molten state solution of two or more transition metals on cooling forms alloy.

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