ncert.nic.in : Class XII Chemistry Question Paper Model National Council of Education Research & Training

Board : National Council of Education Research & Training
Subject : Class XII Chemistry
Document type : Model Question Paper
Website : ncert.nic.in

Download Model/ Sample Question Papers : https://www.pdfquestion.in/uploads/6158-Chemistry.pdf

Chemistry Class XII Model Question Paper :

Time : 3 Hrs.
Max. Marks 70
General Instructions
1. All questions are compulsory.
2. Marks for each question are indicated against it.

Related : National Council Of Educational Research & Training Business Studies Class XII Model Question Paper : www.pdfquestion.in/181.html

3. Q1 to 8 are multiple choice questions.
4. Q1 to 5 carry one mark each.
5. Q6 to 8 carry two marks each and may have more than one correct answer.
6. Q9 to 15 carry two marks each.
7. Q16 to 25 carry three marks each.
8. Q26 to 28 carry five marks each.
9. Use log tables, if necessary.

1. The molecule, AB of a compound forms cubic lattice where ‘A’ atoms occupy the corners and B atoms occupy the alternate faces of the unit cell. The formula of the compound is
(a) A2B
(b) AB2
(c) AB
(d) A2B2 1

2. For the given reaction 2A + B ? C + D, the rate constant is 1.5 × 10–4 s–1. What is the order of the reaction?
(a) one (b) two (c) zero (d) three 1
3. Which of the following is isostructural with XeF4?
(a) ICl4 2–
(b) ICl4 –
(c) SO4 2–
(d) SF4 1

4. What is the coordination number of Co in [Co(NO2)2 (en)2]+ 1
(a) 4
(b) 5
(c) 6
(d) 3

5. C6H5NH2 and C6H5CH2NH2 can be distinguished by 1
(a) Fehling’s test
(b) Isocyanide test
(c) Adding NaNO2 + HCl
(d) Iodoform test

Q6-8 may have more than one correct answer.
6. Four metals A, B, C and D have E° values: – 0.76V, 0.34V, –2.13 V and 0.44V respectively. What is the correct order of their increasing oxidising power? 2
(a) A > B > C > D
(b) D > B > A > C
(c) D > A > B > C
(d) C> D > A > B

7. In which of the following pairs of oxometal ions, the oxidation state of central metal atom is equal to its group number? 2
(a) MnO4 – , Cr2O7 2–
(b) CrO4 2– , MnO4 2–
(c) VO2 +, CrO4 2–
(d) VO2 +, TiO2

8. Starting from bromoethane, the formation of which of the following compound requires more than one step of reaction? 2
(a) Methoxyethane (b) Ethanol
(c) Ethanoic acid (d) Ethene

9. An analysis shows that ferrous oxide has the formula Fe0.93 01.00. What fraction of iron exists as Fe2+ and Fe3+? 2
10. Explain the following:
a) One gram of pulverised wood burns faster than one gram piece of wood.
b) An increase of 10K in temperature rarely doubles the kinetic energy of particles
but this much increase in temperature may be enough to double the rate of reaction.2
OR

Show that in case of first order reaction the time taken for 99.9% of the reaction to take place is ten times that required for 50% of the reaction.

11. Give reason 2
a) PCl5 acts as an oxidising agent.
b) Dinitrogen is chemically inert.

12. Discuss the magnetic behaviour of [Fe(CN)6]3– and [FeF6]3–.
14. Give IUPAC name of the ionisation isomer of [Cr (NH3)5Br]SO4. Draw the 2 structures of optical isomers of [CoBr2(Ox)2]3–

15. In summer, a given sample of milk turns sour at 27°C in 48 hours. In a 2 refrigerator at 2°C, milk can be stored three times longer before it sours. Calculate the activation energy of the souring of milk. R=8.31 JK–1 mol–1

16. Find the Gibbs energy change of the cell at 298K. 3 Cr |Cr3+ (0.1M)|| Cu2+(0.01M) + |Cu. Given E° Cr3+ / Cr = – 0.75V, Cu2+/Cu = +0.34V, F = 96500C.

17. Differentiate between the following 3
(a) Multimolecular colloids and macromolecular colloids
(b) Coagulation and peptisation
(c) Activity and selectivity of catalyst.

18. Give the principle of contact process for the manufacture of sulphuric acid. 3
Give an equation to show oxidising property of sulphuric acid.
OR
How will you prepare
a) HBr from NaBr
b) SO2 from H2SO4
c) XeO3 from XeF6?

19. Account for the following 3
a) Transition metals have high enthalpy of atomization.
b) Mn2+ compounds are more stable towards oxidation than Fe2+ compounds.
c) Cu2+ ion is coloured while Zn2+ ion is not.

20. Explain with the help of electronic effects, ‘generally haloalkenes undergo nucleophilic substitution reactions whereas haloarenes undergo electrophilic substitution reactions’. 3