Class 11 Chemistry NEB Past Questions

1. What is the mode of hybridization of B in BF₃. Predict the geometry of such molecule.

2. Why has ammonia got trigonal pyramidal geometry though nitrogen shows sp³ hybridization?

3. Write an example of a molecule having trigonal pyramidal geometry. What is the mode of hybridization on central atom of the molecule?

4. How is sodium benzoate converted to benzene hexachloride?

5. What happens when i. Sodium benzoate is heated with sodalime. ii. Chlorobenzene is heated with LiAlH₄?

6. Write down correct reactions for the conversion of ethyne into BHC.

7. Name and state the principle which goes against Bohr's fixed orbit.

8. Write the electronic configuration of i. Cl ii. Cr

9. What designation is given to an orbital having i. n=3 and l=1 ii. n=3 and l=0?

10. What are the four quantum numbers of 19th electron of an element having atomic number 24?

11. Explain main postulates of Bohr's theory of atomic model. How did this theory justify the origin of spectral lines in hydrogen atom?

12. Why does hydrogen atom produce so many spectral lines eventhough it contains one electron? Draw a well-labelled diagram to explain the various spectral series observed in it.

13. Identify the four quantum numbers of 19th electron of an element having atomic number 24.

14. What is the conclusion made by de-Broglie? Write its mathematical relationship.

15. How is hydrogen spectra originated according to Bohr's theory? Draw and name the various spectral series observed in the spectrum of hydrogen atom.

16. How did Bohr's theory explain the origin of spectral series in the spectrum of hydrogen atom? Name and sketch the various spectral series observed.

17. Write down the Lewis structure of the following species: i. N₂O ii. PO₄³⁻

18. C in CH₄ gets sp³ hybridization. Give reason.

19. How would you confirm that B in BF₃ gets sp² hybridization?

20. Give an example of each of such molecule having i. Polar covalent bond ii. Non-polar covalent bond iii. Intermolecular hydrogen bond iv. Intramolecular hydrogen bond

21. ii. ammonia is soluble in water.

22. Write down the Lewis structure of i. NO₃⁻ ii. H₂O₂

23. Write down the Lewis structure of each of the following: i. H₂O⁺ ii. N₂O

24. Predict the mode of hybridization B in BF₃ and write any two features of such hybridization.

25. ii. SO₂

26. ii. PO₄³⁻

27. ii. N₂O

28. Write down the Lewis structure of each of the following species: i. NO₃⁻ ii. SO₂

29. Give proper reasons: i. CO₂ molecule gets linear structure ii. ammonia is soluble in water.

30. ii. H₂O₂

31. Give an example of each of such molecule having i. polar covalent bond ii. intra-molecular hydrogen bond iii. net dipole moment zero iv. resonance structure

32. C in C₂H₂ gets sp hybridization, why?

33. i. N₂O

34. i. NO₃⁻

35. i. H₂O⁺

36. i. NO₃⁻

37. i. CO₂ molecule gets linear structure

38. Define equilibrium constant. What information would you expect when equilibrium constant Kc > 1?

39. How does the value of equilibrium constant (Kc) predict the direction of the chemical reaction?

40. Write Short Notes On: Application of Le-Chatelier's principle in chemical equilibrium.