Chemistry – Important Questions Bank for Gujarat (12th Std) HSC Board Exam 2020

CHEMISTRY – IMPORTANT QUESTION BANK

1. Write a short note on intermolecular attraction forces. Melting point of P4 is more than that of N. Why?
2. Give Fisher projection formula of Bromochlorofluoro methane and glyceraldehydes.
3. What is meant by Molal Elevation constant? Derive formula for Molal Elevation constant.
4. Write points of tendency of transition metal ions to form complex compounds.
5. How many millimoles of CO2 will dissolve in 900 ml water, when CO2 gas is passed from water at 25°C.? (Kg = 6.02 x 10-4 bar and partial pressure of CO2 is 2 x10-8 bar).
6. Mention the uses of Lanthanides.
7. Explain Wolff-Kishner and Clementon reduction reactions.
8. Write a short note on: Frenkel Defects.
9. Discuss the industrial production of H₂SO₄ by contact process with figure.
10. State and explain Henry’s law and give its limitations with graph.
11. Write Second Law of Thermo-dynamics and its limitations.
12. “Although first ionization energy is less than second ionization energy, M1+ compounds of transition elements cannot be made easily in comparison to M2+ compounds.” Explain.
13. Explain Filler, Plasticizer and Anti-oxidants.
14. Give the organic conversion in two steps with conditions salicylaldehyde from chlorobenzene.
15. Write a note on Breeder Reactor.

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16. Mention equations of the formation of XeF₂, XeF₄ and XeF₆ with their structures
17. Explain hybridization, geometrical shape and magnetic properties of complex compound K4[Fe(CN)6].
18. Write a short note on “Werner’s theory”.
19. Give the classification of Vitamins. Which disease arises due to deficiency of vitamins in detail?
20. Half life time of ²²⁶Ra is 1620 years. How many α-particles will be released per minute from 2.5 gm. ²²⁶ Ra sample? Each ²²⁶Ra nucleus releases one α -particle.
21. Write the Second law of Thermodynamics. Discuss:’ Free energy and Second law of Thermodynamics.
22. (i) How many defects exist in the arrangement of constituent particles of 7.45 g KCl? [K = 39, Cl = 35.5] (ii) A compound has a bcc structure in which O-2 ion are located at the corner of cube, B+ ion at the center of cube and A+ ion occupy ¼ part of tetrahedral void. Derive the formula of above crystal structure.
23. How many millimoles of CO2 will dissolve in 900 ml water, when CO2 gas is passed from water at 25°C? (Kg = 6.02 x 10-4 bar and partial pressure of CO2 is 2 x10-8 bar).
24. In 1^st transition series the oxidation state of elements on both ends is lower. Explain.
25. Derive formula of Langmuir Absorption Isotherm and express the equation at low and high pressure situations.
26. [Ni F4]2- is diamagnetic, whereas [Ni(CN)4]2- is paramagnetic. Explain.
27. Write a short note on: Friedel – Crafts’ reactions of Methoxybenzene.
28. What is meant by HDP and LDP? Explain Modification in properties of polymer substances.
29. Give scientific reason: Rate of reaction increases in the presence of catalyst.
30. The rate of constant of a first order reaction is 60 S^-1. What will be the time taken for concentration to be 1/6 of the initial concentration?

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31. Explain briefly Self condensation polymerization polymer of Polyamide group.
32. The decomposition of N205 dissolved in Carbon tetrachloride decomposes at definite temperature as follows. N205 (solution) = 2 NO2 (solution) +1/2 02(g).This reaction is of 1st order and its rate constant is 5.0 x10-4 sec-1. For this reaction initial conc. of N205 is 0.25 mole / litre.
    1.  What time will be required for completion of 75% of reaction
    2. What will be the concentrations of N205 and NO2 after 30 minutes from the start of the reaction?

33. What are Carbon fibres? Give the uses of Carbon fibres.
34. Write points of tendency of transition metal ions to form complex compounds.
35. Calculate the rate of α – particles per second obtained from 1 gram of radium. The atomic weight of radium is 226 and its half-life period is 1620 years.
36. The potential of the following given cell is 0.59 volt. Calculate the ionic product of Water (Kw). Pt / H2(1 atm) / KOH(o.01M) // HCl(o.o1M) / H2 (1 atm) / Pt.
37. Distinguish between: Electrochemical cell and Electrolytic cell.