(English Version)
Note :
(i) You must write the subject-code/paper-code 053 in the box provided on the title page of your answer-book.
(ii) Make sure that the answer-book contains 32 pages (including title page) and are properly serialled as soon as you receive it.
(iii) Question/s attempted after leaving blank page/s in the answer-book would not be evaluated.
(iv) There will be one theory paper comprising of 21 questions. All questions are compulsory.
(v) Question Nos. 1 will have 20 sub-parts and each part will carry 1 mark.
(vi) Question Nos. 2 to 15 will be of two marks each.
(vii) Question Nos. 16 to 19 will be of three marks each.
(viii) Question Nos. 20 and 21 will be of five marks each.
(ix) Use of un-programmable calculator is allowed.
(x) Punjabi and Hindi Versions are true translation of English Version.
Complete hydrolysis of DNA/RNA gives a pentane sugar, phosphoric acid and nitrogen containing heterocyclic base. In DNA, sugar is β-D-2-deoxyribose and in RNA, sugar is β-D-ribose. DNA has four bases i.e. adenine, guanine, cytosine and thymine. In RNA instead of thymine, the base is uracil and other three bases are same.
(i) Name the bases present in DNA.
(ii) Name the bases present in RNA.
(iii) What is nucleotide?
(iv) Name the sugar present in DNA.
(v) Name the sugar present in RNA.
True / False :
(vi) Lower aldehydes are soluble in water.
(vii) Ethers have dipole moment due to angular shape.
(viii) Oxalato ion is tridentate ligand.
(ix) Ethylene diamine is an example of bidentate ligand.
(x) Carboxylic acids are weaker acids than alcohols.
(xi) When mercuric iodide is added to aqueous KI solution :
(A) Freezing point is raised (B) Freezing point does not change
(C) Freezing point is lowered (D) Boiling point does not change
(xii) Cell used in wrist watch is :
(A) Dry cell (B) Fuel cell (C) Mercury cell (D) None
(xiii) The half life period for first order reaction is ________ of its initial concentration.
(A) Dependent (B) Independent (C) Property (D) None
(xiv) In cold countries ethylene glycol is added to water in radiators. This results in :
(A) Lowering of freezing point (B) Reducing viscosity
(C) Reducing specific heat (D) Making water better conductor
(xv) Sea water is converted into fresh water based upon :
(A) Diffusion (B) Osmosis (C) Plasmolysis (D) Reverse Osmosis
(xvi) C2H5Cl on heating with alcoholic KOH will produce :
(A) C2H5OH (B) C2H4 (C) C2H6 (D) C2H2
(xvii) Which is most acidic ?
(A) CF3COOH (B) CCl3COOH (C) CBr3COOH (D) CH3COOH
(xviii) Carboxylic acids are reduced by red P and HI to :
(A) Alkanes (B) Alcohols (C) Alkenes (D) Aldehyde
(xix) Stephen’s reduction is used to prepare aldehyde from :
(A) Alcohol (B) Alkyl cyanide (C) Alkanones (D) Acid chloride
(xx) Which of the following species is not expected to be ligand ?
(A) NO (B) NH4+ (C) NH2CH2CH2NH2 (D) CO
2. Define ligand. Give one example of hexadentate ligand.
3. Give two differences between double salt and coordination compound.
4. How phenol is converted into picric acid? OR Explain esterification reaction.
5. How will you convert benzene into benzophenone? OR Why do aldehyde and ketones have high dipole moment?
6. Why methyl amine has less boiling point than methanol?
7. Explain coupling reaction.
8. Give two differences between DNA and RNA.
9. Define ideal solution and write one characteristic.
10. Calculate freezing temperature of solution containing 54 g glucose in 250 g water (Kf = 1.86).
11. Molar conductivity at infinite dilution of Al2(SO4)3 is 858 S cm² mol⁻¹. Calculate molar ionic conductivity of Al³⁺ ion.
12. What are strong and weak electrolyte? Give one example.
13. First order reaction has rate constant k = 5.5×10⁻¹⁴ s⁻¹. Find half life.
14. What is rate of reaction? Write two factors affecting rate.
15. Explain why Cu⁺ ion is not stable in aqueous solution.
16. In first order reaction is 20% complete in 10 minutes. Calculate time for 75% completion.
17. Write Kolbe’s reaction to prepare salicylic acid OR Give reason for higher boiling point of ethanol.
18. (a) Why amide is more acidic than amine?
(b) Why does silver chloride dissolve in methylamine solution?
19. Write Nernst equation and calculate EMF of cell at 298 K.
20. (a) Give three differences between SN1 and SN2.
(b) Convert 2-bromopropane to 1-bromopropane.
OR
(a) Write short notes on :
(i) Finkelstein reaction
(ii) Hunsdiecker reaction
(iii) Wurtz reaction
(b) Convert :
(i) Ethyl chloride to ethyl alcohol
(ii) Ethyl chloride to ethane
21. (a) What is lanthanide contraction? Give causes.
(b) La(OH)3 is more basic than Lu(OH)3. Why?
OR
(a) Scandium is transition element but Zinc is not. Explain.
(b) Chromium is hard metal while mercury is liquid. Why?
Chemistry Class 12 - Answer Key (Paper Code: 053)
Complete solutions and answer key for the Chemistry theory paper. Ideal for students appearing for board exams and competitive entrance tests.
Section A: 1-Mark Questions (i to xx)
I. Comprehension Based (DNA/RNA)
(i) Bases in DNA: Adenine (A), Guanine (G), Cytosine (C), and Thymine (T).
(ii) Bases in RNA: Adenine (A), Guanine (G), Cytosine (C), and Uracil (U).
(iii) Nucleotide: It is a chemical compound consisting of a nitrogenous base, a pentose sugar, and a phosphate group.
(iv) Sugar in DNA: β-D-2-deoxyribose.
(v) Sugar in RNA: β-D-ribose.
II. True or False
| Q. No | Statement | Answer |
|---|---|---|
| (vi) | Lower aldehydes are soluble in water. | True |
| (vii) | Ethers have dipole moment due to angular shape. | True |
| (viii) | Oxalato ion is tridentate ligand. | False (It is Bidentate) |
| (ix) | Ethylene diamine is a bidentate ligand. | True |
| (x) | Carboxylic acids are weaker acids than alcohols. | False (They are stronger) |
III. Multiple Choice Questions (MCQs)
(xi) (A) Freezing point is raised. (Explanation: Due to the formation of complex K2[HgI4], the number of ions decreases).
(xii) (C) Mercury cell.
(xiii) (B) Independent. (For 1st order, t1/2 = 0.693/k).
(xiv) (A) Lowering of freezing point.
(xv) (D) Reverse Osmosis.
(xvi) (B) C2H4 (Ethene).
(xvii) (A) CF3COOH. (Strongest due to -I effect of 3 Fluorine atoms).
(xviii) (A) Alkanes.
(xix) (B) Alkyl cyanide.
(xx) (B) NH4+. (Lacks a lone pair to donate).
Section B: 2-Mark Questions (Highlights)
Q2. Hexadentate Ligand: EDTA (Ethylenediaminetetraacetate).
Q13. Half Life Formula: t1/2 = 0.693 / k
Q15. Cu+ Stability: Cu+ is unstable in aqueous solution because it undergoes disproportionation to Cu2+ and Cu(s) due to the much higher hydration energy of Cu2+.
Section C: 3-Mark Questions (Important Formulas)
Q19. Nernst Equation:
Ecell = E0cell - (0.059 / n) * log([Anion]/[Cation])
