NEB Class 11 Chemistry Question Paper 2076

NEB Class 11 Chemistry Question Paper 2076

NEB Class 11 Chemistry Question Paper 2076




Chemistry - Grade XI
Examination - 2076 (2019)
Regular Students | Subject Code: 112 'B'
Time - 3 hours
Full Marks - 75
Pass Marks - 27 (For Partial Student Only)

Candidates are required to give their answers in their own words as far as practicable. The figures in the margin indicate full marks.
Group 'A'
Attempt any fifteen questions. [15x2=30]
1. Nitrogen reacts with oxygen to give N2O3 and N2O5 respectively. Which law of stoichiometry do this data illustrate? State the law. [1+1=2]
2. Mass of 2x1021 number of atoms of an element is 0.4g. What is the mass of 0.5 mole of the element? [1+1=2]
3. Differentiate between evaporation and boiling. [2]
4. Give reasons. [1+1=2]
i) Gases do not settle at the bottom of the vessel.
ii) Deliquescent substances turns into liquid when exposed to atmospheric air.
5. What is the conclusion made by de-Broglie? Write it's mathematical relationship. [1+1=2]
6. Identify the four quantum numbers of 19th electron of an element having atomic number 24. [2]
7. What is meant by controlled nuclear fission? Write an important application of it. [1+1=2]
8. Write down the Lewis structure of each of the following: [1+1=2]
i) H2O ii) N2O
9. Give an example of each of such molecule having [1+1=2]
i) polar co-valent bond
ii) non-polar covalent bond
iii) intermolecular hydrogen bond
iv) intramolecular hydrogen bond.
10. Which one has greater electron affinity and why? Cl or F [2]
11. Assign oxidation number to the underlined element in each of the following: [1+1=2]
i) N2O2
ii) NaH2PO4
12. State law of mass action. [2]
13. Give reason to show [1+1=2]
i) Al2O3 is an amphoteric oxide
ii) BaO2 is peroxide.
14. What is meant by para-hydrogen? How is it converted into ortho-hydrogen? [1+1=2]
15. What products would you expect when CO is [1+1]
i) heated with H2 in presence of ZnO + Cu
ii) passed over heated caustic soda under pressure.
16. Write down the molecular formula and use of each of the followings:[4x0.5=2]
i) Boric acid
ii) Borax
iii) Silica gel
iv) Sodium silicate
17. Distinguish between alloys and amalgams giving an example of each. [1+1]
18. Why are alkali metals impart characteristics colours when introduced to the flame? [2]
19. Give the IUPAC name of the following organic compounds. [1+1=2]
i) (CH3)3C-OH
ii) CH3COOCH3
20. Define inductive effect and write its one use. [1+1=2]
21. An alkene Ⓐ undergoes ozonolysis to give ethanal and methanal as the major products. Identify Ⓐ and write it's IUPAC name. [1+1=2]
22. Write suitable chemical reaction for the preparation of methane from [1+1=2]
i) sodium ethanoate (CH3COONa)
ii) methyl magnesium iodide (CH3Mgl).v Group 'B' Attempt any five questions. [5x5=25]
23. Define reducing agent giving an example. Balance the following redox reaction by oxidation number or ion-electron method: [1+4=5] MnO2 + HCl → MnCl2 + Cl2 + H2O
24. Explain main postulates of Bohr's theory of atomic model. How did this theory justify the origin of spectral lines in hydrogen atom? [4+1=5]
25. Describe laboratory method of preparation of ethene. Suggest a chemical test to distinguish ethene from ethane. [4+1=5]
26. Why can't HBr and HI be prepared by heating Conc. H2SO4 with bromide and iodide respectively? Write down correct reactions to prepare them. How would you test the presence of Br− ions in its aqueous solution? [2+2+1=5]
27. Give the chemistry of plaster of pairs. [5]
28. How is sulphurdioxide gas prepared in laboratory? Write reactions to show SO2 acts as both an oxidising as well as a reducing agent. [3+2=5]
29. a) A trivalent metal oxide contain 31.6% of oxygen. What is the atomic mass of the metal? [2]
b) 16.8 gm of NaHCO3 when heated produces 9gm of Na2CO3 according to the following reaction: [3]
2NaHCO3 ---△---> Na2CO3 + CO2 + H2O
Chemical Reaction
i) find the percentage purity of the NaHCO3
ii) how much volume of CO2 will be produced at 1 atmospheric pressure and 27°C temperature.
Group 'C'
Attempt any two questions: [2x10=20]
30. a) Write down the principle and procedure with self-explanatory diagram for the manufacture of nitric acid by catalytic oxidation of ammonia. How does Conc. HNO3 react with: [3+3=6]
i)KI
ii)Znv
b) Explain, why? [2+2=4]
i) Conc. HNO3 is stored in dark bottle.
ii) iron becomes passive when treated with Conc. HNO3
31. State Boyle's Law and draw:
i) P vs V
ii) V vs 1/p and
iii) Pv vs p graphs to support Boyle's law. What is the practical
significance of this law? A toy balloon blown up at 10°C, has a volume 960 cc. At this stage the balloon is distended to 7/8 of its maximum stretching capacity. Will the balloon burst, if it is brought to a room having temperature 10°C? If not, calculate the temperature at which the balloon burst. [2+3+1+4=10]
32. Explain the principle and procedure involved in the manufacture of washing soda by ammonia-soda process. Sketch a well-labelled diagram for it. How would you convert washing soda into
i) soda ash ii) sodium silicate respectively?
Write down important uses of washing soda. [6+2+2=10]
33. Write short notes on any two. [5x2=10]
i) Detection of nitrogen in the organic compound.
ii) Advantages of modern periodic table.
iii) Characteristics of homologous series.
iv) Relationship between Kp and Kc.