Chemistry (Theory)
Class – XII
Time allowed: 3 hrs M.Marks: 70
General instructions:-
i. All questions are compulsory.
ii. Internal choices has been provided in some questions you have to attempt only one of the choice in such questions.
iii. Q.No 1 to 8 are very short answer type questions, carrying one mark each.
iv. Q. No. 9 to 18 are short answer type questions, carrying two mark each.
v. Q.No. 19 to 27 are also short answer questions, carrying three mark each.
vi. Q.No. 28 to 30 are long answer type questions, carrying five mark each.
vii. Use of calculators is not permitted. However you may use log tables, if necessary.
Q1. What is hydrometallurgy?
Q2. Write IUPAC name of the complex compound: [Co Cl2 (en)2] NO3 .
Q3. Among the isomeric alkanes of molecular formula C5H12, identify the one that on photochemical chlorination yields three monochlorides.
Q4. Write IUPAC name of CH3-CH=CH-CH2- CHO.
Q5. What are biodegradable polymers? Give one example.
Q6. Define 12-16 compounds.
Q7. Name the process used for refining of (i) Nickel.
Q8. People living at high altitude generally suffer from anoxia , Explain.
Q9. C4H8Cl2 (A) on hydrolysis forms C4H8O (B) which forms an oxime, but does not reduce Fehling solution. B also gives iodoform test. Identify A and B and explain reactions.
Q10. Give reasons:
(i) Why are amines basic in nature?
(ii) Ethylamine is more basic than aniline.
Q11. Silver crystallizes in fcc lattice. If edge length of the cell is 4.00x10-8 cm and density is 10.5 g cm-3, calculate the atomic mass of silver.
Q12. State Henry’s law and mention some of its important applications.
Q13. Draw figure to show splitting of d-orbitals in an octahedral crystal field?
Q14. Account for the following:
a)Haloalkanes undergo nucleophilic substitutions while haloarenes undergo electrophilic substitution.
b)Haloalkanes react with KCN form alkylcyanides while isocyanides are formed with AgCN.
Q15. Can PCl5 acts as oxidizing agent? Justify your answer by giving reactions.
Q16. Which vitamin is called as Riboflavin? What are its sources? What is the disease caused by the deficiency of this vitamin?
Q17. What are homopolymers and copolymers? Can homopolymers be of addition as well as condensation type? Give some examples to justify your answers.
Q18. On dissolving 3.24g of sulphur in 40g of benzene the b.p of the solution was higher than that of benzene by 0.81K. Kb value for benzene is 2.53Kkgmol-1. Find the molecular formula of sulphur. Atomic mass of sulphur = 32.
Q19. (a) How do antiseptics differ from disinfectants? Explain with examples.
(b) Define the term chemotherapy.
Q20. (i) Calculate the emf of the cell in which the following reaction takes place.
Ni (s) + 2 Ag+ (0.002 M) → Ni 2+ (0.160 M) + 2 Ag (s)
Given that E0Cell = 1.05V
(ii) What are the products obtained at anode and cathode when aqueous NaCl is electrolyzed with Pt electrodes?
Q21. (i) Chromium crystallizes in bcc structure. Its atomic diameter is 245 pm, find density. Atomic masses of: Cr = 52u , NA =6.022 x 1023mol-1
(ii) Atoms of element B form hcp lattice and those of A occupy 2/3 of tetrahedral voids. What is the formula of the compound b/w A and B?
Q22. (a) If an electric field is applied to a colloidal sol, the dispersed phase particles are found to move towards the electrode of opposite charge. If however, the dispersed phase is made stationary, the dispersion medium is found to move in the opposite direction. What is the term used for such movement of dispersion medium ?
(b) A sol is prepared by addition to excess AgNO3 solution in KI solution. What charge is likely to develop on the colloidal particles ?
(c) Out of glucose, urea and dodecyl trimethyl ammonium chloride, which one forms micelles in aqueous solution above certain concentration ?
Q23. 0.2964 g of copper was deposited on passage of a current of 0.5 ampere for 30 minutes through a solution of copper sulphate. Calculate the atomic mass of copper.
Q24. 19.5 g of CH2FCOOH is dissolved in 500 g of water. The depression in the freezing point of water observed is 1.00C. Calculate the van’t Hoff factor and dissociation constant of fluoroacetic acid.
Q25. How will you bring about the following conversions –
(i) Propanal to Butanone
(ii) Benzene to phenyl acetic acid
(iii) Benzaldehyde to Benzophenone.
Q26. 100 gm of Liquid “A” ( Molar mass 140 g/mol) was dissolved in 1000gm of liquid “B” ( Molar mass 180 g/mol). The vapour pressure of pure “B” was found to be 500 torr. Calculate the vapour pressure of pure “A” and its vapour pressure in solution is recorded as 475 torr.
Q27. Explain following –
i. Activation Energy
ii. Threshold Energy
iii. Activated complex.
Q28. (a) Write mechanism of acid dehydration of ethanol to yield ethene.
(b) Explain – 1. Kolbe Reaction 2. Reiemer – Tiemann Raction.
OR
Explain –
i. Acetylation
ii. Transeterification
iii. Carbylamine reactio
vi. HVZ reaction
v. Schiff’s base formation.
Q29. Describe the steps involved in the preparation of either potassium dichromate from sodium chromate or potassium permanganate from manganese dioxide.
Q30. How do you account for the following? Give reasons:
(i) Oxidation of toluene with CrO3 to Benzaldehyde is carried out in presence of acetic anhydride
(ii) Although Aldehydes are easily oxidisable yet propanal can conveniently be prepared by the oxidation of propanol by acidic dichromate.
(iii) In the preparation of acetaldehyde from ethanol by oxidation, it is distilled out as it is formed.
(iv) Formation of oximes and other ammonia derivatives from carbonyl compounds require slightly acidic medium for maximum rate. Benzaldehyde does not undergo aldol condensation whereas acetaldehyde does.
More CBSE Sample papers: Click Here