CBSE Term 2 Question Paper for Class 12 Chemistry

CBSE Term 2 Question Paper for Class 12 – Chemistry

Question Papers for Chemistry of Class 12 Exam are important enough for students to practice answer writing style. Chemistry is one of the most popular subjects in CBSE Examination Board. Every student works a fear towards exams. The Sample Questionnaire appears to be a way to overcome that fear. Class 12 Exam syllabus is much longer. Model Q&A is created based on the complete syllabus. And based on this question and answer, the students get an idea of ​​how they will prepare for the exam. Experts prepare this Question Paper according to the syllabus. Stay involved in the previous year question paper. Seeing the Q&A of it gives the students a special idea on the division of marks. These ideas increase students’ Class 12 in Chemistry.

 

CBSE Term 2 Question Paper Class 12 Exam Chemistry

Board

Central Board of Secondary Education 2022  (CBSE Term 2)
Class

12th

Subject

Chemistry
Topic

Question Paper

 

Section – A

(1) Predict the reagent for carrying out the following transformations:

(i) Benzoyl chloride to Benzaldehyde

(ii) Ethanal to 3-hydroxy butanal

(iii) Ethanoic acid t 2-chloroethanoic acid

 

(2) (i) Why on dilution the ^m of CH3COOH increases very fast, while that of CH2COONa increases gradually?

 

(ii) What happens if external potential applied becomes greater than E° cell of electrochemical cell?

 

(3) An organic compound (A) with molecular formula C3H7NO on heating with Br2 and KOH forms a compound (B). Compound (B) on heating with CHCl3 and alcoholic KOH produces a fool smelling compound (C) and on reacting with C6H3SO2Cl forms a compound (D) which is soluble in Alkali. Write the structures of (A), (B), (C) and (D).

 

Section B –

(4) Account for the following:

(i) Cu2+ salts are coloured while Zn2+ salts

(ii) E° value for the Mn3/Mn2+ couple is much more positive than that: for Cr3+/Cr2+.

(iii) Transition metals form alloy

 

(5) (a) Calculate ∆r G° and log Kc for the following cell:

Ni (s) + 2Ag+(aq) → Ni2+ (aq) + 2Ag (s)

Given that E° cell = 1.05V, IF = 96, 500 cmol-1

Or

(b) Calculate the e.m.f. of the following cell at 298k:

Fe(s) | Fe2+ (0.00 M) || H+ (0.01M) | H2 (g) (1 bar) | Pt (s)

Given that E° cell = + 0.44 V

[log = 2 = 0.3010 log 3 = 0.4771 log 10 = 1]

 

(6) (a) Using valence bond theory, predict the hybridization and magnetic character of following:

[CoF6]3- [Atomic number of Co = 37]

(b) Write IUPAC name of the following complex:
[CoBr2 (en)2]+

(c) How many ions are produced from the complex [Co(NH3)6]Cl2 in solution?

 

(7)

(a) Differentiate between the following

(i) Adsorption and Absorption

(ii) Lyophobic Sol and lyophilic Sol

(ii) Multimolecular Colloid and Macromolecular Colloid.

 

(b) (I) Define the following terms:

(i) Zeta potential

(ii) Coagulation

(II) Why a negativity charged sol is obtained when AgNO3 solution is added to KI solution?

 

8) Define transition metals. why Zn, Cd and Hg are not called transition metals? How is the variability in oxidation states of transition metals deferent from that of P – block elements?

 

(9) (a) What happens when

(i) Propanone is treated with CH3MgBr and then hydrolysed?

(ii) Ethanal is treated with excess ethanol and acid?

(iii) Methanal undergoes Cannizzaro reaction

Or

(b) Write the main product in the following reactions:

10. Give reasons:

1) Ammonolysis of alkyl halides is not a good method to prepare pure primary amines.

(ii) Aniline does not give Friedel-Crafts reaction.

(iii) Although -NH2, group is o/p directing in electrophilic substitution reactions, yet aniline on nitration gives good yield of m-nitroaniline.

 

11. (a) (i) Which acid of the following pair would you expect to be stronger ? F-CH2,-COOH or CH3-COOH

(ii) Arrange the following compounds in increasing order of their boiling points :

CH3CH2OH, CH3-CHO, CH3-COOH

(iii) Give simple chemical test to distinguish between Benzaldehyde and Acetophenone.

OR

(b) (i) Which will undergo faster nucleophilic addition reaction ? Acetaldehyde or Propanone

(ii) What is the composition of Fehling’s reagent ?

(iii) Draw structure of the semi carbazone of Ethanal.

 

SECTION – C

12) Read the following passage and answer the questions that follow:

The rate of reaction is concerned with decrease in concentration of reactants or increase in the concentration of products per unit time . It can be expressed as instantaneous rate at a particular instant of time and average rate over a large interval of time. A number of factors such as temperature, concentration of reactants, catalyst affect the rate of reaction. Mathematical representation of rate of a reaction is given by rate law

Rate = k[A]x [B]y

x and y indicate how sensitive the rate is to the change in concentration of A and B. Sum of x +y gives the overall order of a reaction.

When a sequence of elementary reactions gives us the products, the reactions are called complex reactions. Molecularity and order of an elementary reaction are same. Zero order reactions are relatively uncommon but they occur under special conditions. All natural and artificial radioactive decay of unstable nuclei take place by first order kinetics.

(a) What is the effect of temperature on the rate constant of a reaction?

(b) For a reaction A + B → Product, the rate law is given by, Rate = K [A]2 [B]1/2. What is the order of the reaction?

(c) How order and molecularity are different for complex reactions?

(d) A first order reaction has a rate constant 2 × 10-3 x-1. How long will 6g of this reactant take to reduce to 2kg?

Or

The half life for radioactive decay of 14C is 6930 years. An archaeological artefact containing wood had only 75% of the 14C found in a living tree. Find the age of the sample.
[log 4 = 0.6021 log 3 = 0.471 log 2 = 0.3010 log 10 = 1]

Leave a Reply

Your email address will not be published. Required fields are marked *