National Examinations Board (+2)
+2 Science (Class 11 and 12)
Class 11 · NEB 2076 (old course)
Course Title: Chemistry (Chem)
Full Marks: 75Pass Marks: 27Time: 3 hrs
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.(15×2=30)
- 1.2
Nitrogen reacts with oxygen to give and respectively. Which law of stoichiometry do this data illustrate ? State the law. [1+1]
- 2.2
Mass of number of atoms of an element is . What is the mass of mole of the element ? [1+1]
- 3.2
Differentiate between evaporation and boiling. [2]
- 4.2
Give reasons [2] i) Gases do not settle at the bottom of the vessel. [1] ii) Deliquescent substances turns into liquid when exposed to atmospheric air. [1]
- 5.2
What is the conclusion made by de-Broglie? Write its mathematical relationship. [1+1]
- 6.2
Identify the four quantum numbers of electron of an element having atomic number 24. [2]
- 7.2
What is meant by controlled nuclear fission ? Write an important application of it. [1+1]
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- 8.2
Write down the Lewis structure of each of the following: [2] i) [1] ii) [1]
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- 9.2
Give an example of each of such molecule having [2] i) polar co-valent bond [0.5] ii) non-polar covalent bond [0.5] iii) intermolecular hydrogen bond [0.5] iv) intramolecular hydrogen bond. [0.5]
- 10.2
Which one has greater electron affinity and why ? or [2]
- 11.2
Assign oxidation number to the underlined element in each of the following: [2] i) [1] ii) [1]
- 12.2
State law of mass action. [2]
- 13.2
Give reason to show [2] i) is an amphoteric oxide [1] ii) is a peroxide. [1]
- 14.2
What is meant by para-hydrogen ? How is it converted into ortho-hydrogen ? [1+1]
- 15.2
What products would you expect when is [2] i) heated with in presence of [1] ii) passed over heated caustic soda under pressure [1]
- 16.2
Write down the molecular formula and one use of each of the following: [2] i) Boric acid [0.5] ii) Borax [0.5] iii) Silica gel [0.5] iv) Sodium silicate. [0.5]
- 17.2
Distinguish between alloys and amalgams giving an example of each. [1+1]
- 18.2
Why are alkali metals impart characteristic colours when introduced to the flame ? [2]
- 19.2
Give the IUPAC name of the following organic compounds: [2] i) [1] ii) [1]
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- 20.2
Define inductive effect and write its one use. [1+1]
- 21.2
An alkene undergoes ozonolysis to give ethanal and methanal as the major products, identify and write its IUPAC name. [2]
- 22.2
Write suitable chemical reaction for the preparation of methane from [2] i) sodium ethanoate () [1] ii) methyl magnesium iodide (). [1] GROUP: B | Attempt any five questions. | 5×5=25
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