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Hello Grade 12 Students out there, we’re going to provide you NEB Class 12 Chemistry Grade Increment (Supplementary) Exam Paper 2080 with subject code – 3021 ‘A’ which examination was held on the year 2080/2023 and you can download the neb grade xii (12) Chemistry subject grade increment (supplementary) exam question paper of the year 2080-2023 in PDF format. Please check and download pdf file grade 12 Chemistry Exam question paper of the year 2023-2080 Nepal. The Exam Question provided below – NEB Class 12 Chemistry Grade Increment (Supplementary) Exam Paper 2080 for the board exam 2079 and onwards. And it is based on the latest NEB Syllabus for 2079 and so on. We will be adding more Exam Question Papers of grade xii- class 12 later on. Scroll down to Download NEB Class 12 Chemistry Grade Increment (Supplementary) Exam Paper 2080 Sub. Code: 3021’A’ in pdf format which is 2.15 mb in size. Enjoy!
NEB Class 12 Chemistry Grade Increment (Supplementary) Exam Paper 2080.
NATIONAL EXAMINATIONS BOARD [NEB]
Chemistry
Grade XII-Class 12
Grade Increment (Supplementary)
Examination – 2080 (2023)
(New Course)
Subject Code: 3021 ‘A’
Time – 3 hrs
Full Marks – 75
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Candidates are required to give their answers in their own words as far as practicable. The figures in the margin indicate full marks.
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Attempt all the questions.
Group – ‘A’
Rewrite the correct options of each questions in your answer sheet. 11×1=11
1. Phenol is heated with CHCI3 and aq.KOH than produce salicylaldelyde. This reaction is called.
A) Friedel-crafts reaction B) Rosenmund’s reaction C) Reimer-Tiemannreaction D) Carbyalamine reaction
2. Which of the following reaction is used to distinguish carboxylic acid with other organic compound ?
A) reaction with sodium metal B) reaction with bicarbonate C) reaction with magnesium metal D) reaction with chlorine
3. Silver gets tarnished in air due the reaction with
A) O2 B) CO2 C) H2O D) H2S
4. Lithophone is a mixture of
A) ZnSO, BaSO, B) ZnS BaSO4 C) ZnCO, BaCO, D) ZnS Na2SO4
5. The correct decreasing order of acidic strength of0.1m solution of following acids, is
A) F CHCOOH> FCH COOH+ CICH COOH+ CH COOH
B) FCH COOH> F CHCOOH> CICH COOH> CH3COOH
C) CICH COOH> FCH COOH> F CHCOOH> CH3COOH
D) CH COOH> CICH COOH> FCH COOH> F CHCOOH
6. Another name of grain alcohol is
A) wood alcohol B) methyl alcohol C) ethyl alcohol D) propyl alcohol
7. Primary and secondary amines are distinguished by.
A) Br/KOH B) JfC/O C) HNO D) NH
8. The specific rate constant of 1storder reaction depends on
A) concentration of reactant B) temperature C) time D) concentration of product
9. Calculate number of H” ion present in 1m1 of a solution whose P”=l3
A) 6.02x 107 B) 6.02x 10’ C) 6.02x 10’ D) 6.02x 10″
10. What will be the value of AS for conversion of ice into water when they are in equilibrium ? (Ah = 6KJ/mol)
A) 0. 022KJ K ‘mol ‘ B) 0. 025KJ K ‘mol‘’ C) 0. 027KJ K‘’mol I D) ().029KJ K ‘mol ‘
11. Find out the volume of water to be added to html of 2X DC/ to make it exactly decinormal.
A) 375 ml B) 385 ml C) 380 ml D) 390 ml
Group – ‘B’ 8X5=40
12. Give an example of each of the following reaction
i) Coupling reaction
ii) Hydroboration oxidation
iii) Clemmensen’s reduction
iv) Fehling test
v) Carbonylation reaction 1×5=5
13. An organic compound (A) having molecular formula C4H02 undergoes acid hydrolysis to produce a carboxylic acid (B) and an alcohol (C). When (B) is reduced with LiAlH then the alcohol (C) is produced. 4+1
i) Draw molecular structure of (A) (B) and (C) with proper reaction.
ii) What products would you expect when (A) is reduced with LiAlH ?
14. You are given a bottle containing a mixture off-Xff2, R, H and fi. How would you apply Hoffmann’s method to separate each compound in pure state ? 5
15. Describe rusting theory of Iron. Name the process of preventing iron from rusting. 4+1
16. i) What is meant by transition metal ? 1
ii) Justify giving proper reason. 1+1
a) Transition metals mostly form coloured compounds.
b) Zinc is regarded as non-typical transition metal.
c) Draw splitting of d-orbital in octahedral field showing eg set and t2g set. 2
17. An electrochemical cell is connected by using Aluminum (AI) electrode and silver (Ag) electrode whose standard electrode potential value -1.67 V and +0.80V respectively.
i) Write cell notation of an electrochemical cell indicating anode and cathode. 2
ii) Write down oxidation half and reduction half reaction occurring in the cell. 2
iii) Calculate e.m.f. of the cell. 1
18. Enthalpy of formation of HCO (II, CO2 Ig1 and CNAOH(11 are-286W/mol, -394 KJ/mol and -2010KJ/mol respectively.
i) What is meant by enthalpy of formation ? 1
ii) Write down balanced thermochemical reactions for each of above process. 1
iii) Calculate the enthalpy of combustion of C fI OHtl from the above data. 3
Or
i) Deduce the relation between P” and P°” at 25′ C. 2
ii) The solubility product o AgCl is 1.8x 10’10. What mass ofAgCl (Molecular mass = 143.5) will be precipitate of 0.2 mole ofHC/ solution is added to the saturated solution ofAgC/. 3
19. Represent a regular sequence of reaction of the following sets of organic compounds using suitable catalysts, reagents or conditions.
CH3CHSCH MCI, CHSCHSNH , CH CH CH OH, CH CH2COOH, CH3CH CONH
Or
Formic acid is the first member of carboxylic acid and naturally found ant stings and venom of bee.
i) Draw the molecular formula of formic acid and write its IUPAC name. 1
ii) How is formic acid prepared from
a) chloroform b) ethane-1,2- dioic acid ? 1+1
iii) Distinguish formic acid from acetic acid with a chemical reaction. 1
iv) Why is formic acid more acidic than acetic acid * 1
20. a) Normality factor and titration error are important in analytical chemistry for the determination of variation of the observed result for the same experiment•
i) Distinguish between normality factor and titration error. 2
ii) A chemistry lab-boy weighed 1.31gm of Na2CO, to prepare 250m1 of it’s decinormal solution.
a) Calculate the actual strength of the solution indicating normality factor.
b) Find the volume of water required to be evaporated to make it exactly normal solution.
iii) Calculate the mass of oxalic acid crystal required to neutralization the solution completely. 2+1+2
iv) How would you apply of titration in pharmaceutical industry ? 1
Or
i) Define half-life period of reaction. 1
ii) Why is half-life period of first order reaction independent of the initial concentration. 2
iii) Mention the major application of half life period in biological Scientific research. 1
iv) A first order reaction is 60% complete in 30 minute.
a) Find out the rate constant and half life period. 2
b) Calculate the time required to convert 99% of the reactant into products 1
c) Mention an example to show effect of surface area of reactant on rate of reaction. 1
21. An alcohol (A) of molecular formula C3H8O undergoes Victor Meyer’s reaction to give blue colour at the end of reaction when added KOH solution
i) Draw structural formula and IUPAC name of (A) 1
ii) Give the complete chemical reaction for the Victor-Meyer’s test of(A) 2
iii) Starting from CH MgBr, how would you prepare compound A ? 2
iv) What happens when (A) is oxidised. 1
v) Convert (A) into propene. 2
Or
i) Give proper chemical reaction for the preparation of benzaldehyde from
a) Benzyl chloride b) Toluene 2
ii) Convert benzaldehyde into
a) Toluene b) cinnamic acid. 2
…
NEB Class 12 Chemistry Grade Increment (Supplementary) Exam Paper 2080
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