AHSEC| CLASS 12| CHEMISTRY| QUESTION PAPER - 2022| H.S. 2ND YEAR
2022
CHEMISTRY
Full Marks: 70
Pass Marks: 21
Time: Three hours
The figures in the margin indicate full marks for the questions.
1. A metal crystallies in a body-centred cubic structure. If ‘a’ is the edge length of its unit cell, ‘r’ is the radius of the sphere, what is the relationship between ‘r’ and ‘a’? 1
2. Arrange the following compounds in the increasing order of their boiling points: CH3 -CHO, CH3 -CH2 -OH, CH3 -CH2 -CH3 1
3. Write down the formula of Tetraamineaquachloridocobalt(III) chloride. 1
4. Write the IUPAC name of the following compound: 1
5. What will be the impact on Kf when the molality of a solution is doubled? 1
6. Which is a stronger oxidizing agent-
1
7. pKb of aniline is more than that of methylamine. Why? 1
8. Which of the following compounds can undergo Hell-Volhard-Zelinsky reaction? 1
(i) Benzoic acid (ii) Propanoic acid
9. The freezing point depression constant for water is 1.860Cm-1. If 5.0g of Na2So4 is dissolved in 45g of water, then freezing point is charged by 3.800C. Calculate the Van’t Hoff factor for Na2So4. 2
Or
State Henry’s law. Why do gases nearly always tend to be less soluble in liquids as the temperature is raised? 2
10. Calculate the pH at which the potential of hydrogen electrode will be 0.059V. 2
Or
The Chemistry of corrosion of iron is essentially an electrochemical phenomenon. Explain the reaction occurring during the corrosion of iron in the atmosphere. 2
11. Why H2 and O2 do not react at room temperature? Write the rate equation for the reaction A2+B2-2C, if the overall order of the reaction is zero. 1+1=2
Or
A first order reaction has a rate constant of 0.0051 min-1. If we begin with 0.10M concentration of the reactant, what concentration of reactant will remain in solution after 3 hours? 2
12. Answerer any two:
(a) Write the mathematical expression for the Freundlich absorption isotherm and draw the graph log x/y vs log P. 2
(b) How do emulsifiers stabilize emulsion? Name two emulsifiers. 2
(c) Define shape-selective catalysis. Give an example. 1+1=2
13. Why is it that only sulphide ores are concentrated by froth floatation processes? What is the role of depressants in the froth floatation process of dressing of ores? 1+1=2
14. Answer any two:
(a) Ti4+ compounds are colourless in aqueous solution but Ti3+ compounds are violet coloured. Explain. 2
(b) What is meant by ‘disproportionation’ of an oxidation state? Give an example. 2
(c) Actinoid contraction is greater than lanthanoid contraction. Why? 2
15. (i) Write the IUPAC name of the following compound: 1
[Pt(NO2)(NH3)BrCI]
(ii) How many geometrical isomers will be possible for [Pt(Py)(NH3)BrCI] compound?
Or
Write the hybridization state of central atom of the following co-ordination complexes along with their magnetic properties. 2
[Cu(NH3)4]2+ and [Ni(CO)4]
16. What is the prime cause of depression? Give an example of antidepressant drug. 2
Or
What is the function of a Tranquilizer? Give an example of a compound which can be used both as Antiseptic and Disinfectants. 2
17. Mention the type of Semiconductor when Si doped with P. A soild compound XY has NaCI structure. If the radius of the cation (X+) is 100pm then calculate the radius of the anion (Y-). 1+2=3
Or
What are semiconductors? How electrical conductivity of semiconductors vary with temperature? Give one example of intrinsic semiconductors. 1+1+1=3
18. In the electrochemical cell;
Zn/ZnSO4(0.1M)//CuSo4(0.1M)/Cu, the e.m.f. of the Deniel cell is E1.
When the concentration of ZnSO4 changed to 1.0M and CuSO4 changed to 0.01M, the e.m.f of the cell changes to E2. Establish the relation between E1 and E2. 3
Or
The molar conductance of 0.1m aqueous solution of NH4OH is 9.54 ohm-1cm2mol-1 and at infinite dilution molar conductance is 238ohm-1cm2mol-1. Calculate the degree of ionization of ammonium hydroxide at the same concentration and temperature. 3
19. (a) Define molality of a solution. 1
(b) State Henry’s law. At the same temperature, CO2 gas is more soluble in water than O2 gas. Which one of them will have higher value of KH? 2
20. Decomposition of H2O2 follows a first order reaction. In 50 minutes, the concentration of H2O2 decreases from 0.5 to0.125M in one such decomposition. When the concentration of H2O2 reaches 0.05M, what is the rate of formation of O2? 3
Or
Show that the integrated rate for a first order reaction R 
P is 3
21. What happens, when – (any three) 1+1+1=3
(a) P4O10 is treated with dil. HNO3
(b) CI2 is treated with hot and conc. NaOH
(c) Reaction of ammonia with excess CI2 gas
(d) Orthophosporic acid is heated
22. (a) Write the chemical reactions for following transformations: (any two) 1+1=2
(i) Benzene to Phenol
(ii) Toluene to Benzyl alcohol
(iii) Benzene to Diphenyl
(b) Why aryl halide undergoes electrophilic substitution reaction rather than nucleophilic substitution reaction? 1
23. (a) Identify A and B. 2
(b) Write only the chemical reactions of the following (any one) 1
(i) Carbylamine reaction
(ii) Hoffmann bromamide reaction.
24. (a) Give an example of biodegradable polymer. 1
(b) Match the following correctly 2
Polymer | Monomer |
(a) Natural Ruber | (i) 1.3 Butadiene+Styrene |
(b) Neoprene | (ii) 1,3 Butadiene+acrylonitrile |
(c) Buna-N | (iii) Chloroprene |
(d) Buna-S | (iv) Isoprene |
25. (a) Write the chemical reactions for following transformation: (any two) 1+1=2
(i) Benzyl chloride to benzyl alcohol
(ii) Methyl magnesium bromide to 2-methyl-propan-2-ol
(iii) Acetophenone from phenol
(b) Arrange the following in increasing order of acidity. 1
26. (a) What type of bonding helps in stabilizing the secondary structure of proteins? 1
(b) Answer the following question: (any two)
(i) How are vitamins classified? Name the vitamin deficiency of which causes scurvy. 2
(ii) What is glycogen? How is it different from starch? 2
(iii) Name the protein which is present in hair. What type of protein is this? 2
27. (a) Draw the structure of any one of the following: 1
(i) Chlorous acid (ii) S8
(b) Answer the following questions: (any two)
(i) Are the bond lengths of all five P-CI bonds in PCI5 molecule equal? Justify your answers. 2
(ii) Explain why HNO2 behaves both as oxidizing as well as reducing agent.
(iii) When HCI reacts with finely powdered iron, it forms ferrous chloride, and not ferric chloride. Explain, Why? 2
28. Complete the following reactions: 1x5=5
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