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This is model question paper for class 12 chemistry subject NEB exam for 2077( 2020) only. 

Subject – Chemistry         Full mark = 30

Time – 1:30 hours

GROUP A   (2×5 = 10)

Attempt any five questions.

1. Why do H2O and H2S have dissimilar geometries?

2. Can a solution of 1M NiSO4 be stored in a vessel made up of Copper? If not,why?

        Given: E0Ni++/Ni= -0.25 V and E0Cu++/Cu= +0.34V

3. Predict the criteria of spontaneity in term of free-energy change in exothermic reaction.

4. Convert methanamine to ethanamine and vice- versa.

5. How is TNT prepared? Write its one use.

6.What is meant by peptide bond ? Write the structure of dipeptide.

7. What is Rinman’s green? Write its important uses.

GROUP B ( 5×2 = 10)

Attempt any two questions.

8. What is meant by redox titration? 4 gm of a divalent metal was dissolved in 100cc of 2M H2SO4 (f=1.01) . The excess acid required 30ml of 1N NaOH for complete neutralization. Find the atomic weight of metal.

9. How is mercury extracted from cinnabar?

10.Write short note on :
a. Carbylamine test

b. Aldol condensation reaction

c. Perkin condensation.

GROUP C ( 10×1=10 )

Attempt any one question.

11. Define pseudo order reaction. Derive rate law equation for first order reaction. For a first order reaction, it takes 20 minutes for initial concentration of 0.6 mol/ L to become 0.2 mol/L. What time will it take to become the concentration to 0.06 mol/L ?

12. How is formic acid prepared in laboratory? What happens when nitrobenzene is reduced in acidic, alkaline and electrolytic conditions?

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