Class – XII
Subject :Chemistry 1st Paper
Time : 3 hrs. Marks.75
Group -A
1. | (a) Write down the main postulates of the kinetic theory of gases. | 4 |
(b) What do you mean by σ and  bond? What are the differences between σ and bond. | 4 | |
(c) Describe the electronic concept of oxidation and reduction. Show oxidation and reduction take place simultaneously. | 4 | |
(d) To neutralize 25 ml of NaoH solution at first 10 ml 0.1 m Hcl is added to it. To comple neutralization another 16ml 0.15 m Hcl solution is added calculate the concentration of NaoH solution. | 3 | |
Or, | (a) What is buffer solution? Describe buffer mechanism of acidic buffer solution. | 4 |
(b) Describe Bohr's atom noted with limitations. | 4 | |
(c) Write down the defects of modern periodic table. | 4 | |
(d) Calculate the morality of 10% Na2 CO3 solution. | 3 | |
2. | (a) What do you mean by absolute Zero temperature? Show that a new scale of temperature measurement is found from charles law. | 4 |
(b) What is covalant bond ? How it is formed. Discuss with example. | 4 | |
(c) What do you mean by order of reaction? Show half life of recond order reactiion is inversely proportional to the initial concentration of reactant. | 4 | |
(d) At constant temperature 1.32 H2 gas at 95 kPa pressure and 0.622 N2 gas.at 99 kPa pressure and 1.42 O2 gas. at 75 KPa. Pressure are mixed into a 1.5 L container. Find out the total pressure of the gasses. mixture. | 3 | |
Or, | (a) What is oxidation number? Write down the method of calculating oxidation number for a particular element in a compound. | 4 |
(b) What do you mean by acid and base. Discuss Arheneous and Bronsted lowry concept regarding acids and bases with limitation. | 4 | |
(c) Establish the relationship between Kp and Ke is Kp = Kc for a reversible reaction. | 4 | |
(d) How many molecules are present in 1 ml of nitrogen at STP? | 3 | |
3. | (a) What is hybridization? explain SP3 and SP hybridization with example? | 4 |
(b) What is Rault's law reganding vapour pressure of liquid- liquid mixture. stele it's mathematical representation? | 4 | |
(c) What are the fundamental particles? Write down the characteristics of three stable fundamental particle. | 4 | |
(d) Heating 1.84 mixture of Ca CO3 and Mg CO3 is 0.96 g residue is found. Calculate the percentage of the mixture. ( Cu =40, Mg =24 c = 12, 0 =16) | 3 | |
Or, | (a) What do you mean by ionization potential? Why ionization to 1st potential of N is less then that of O. | 2+2=4 |
(b) Write down differences between nuclear fission and fusion. | 4 | |
(c) Prove that at constant pressure the heat of reaction is equal to the change of it's enthalpy. | 4 | |
(d) Find out PH of 0.02 M NaoH solution. | 3 | |
Group - B | ||
4. | (a) Which is posible or not and why? | 3 |
(b) Which one is stronger then other. HNO3. and H3 PO4. | 2 | |
Or, | (a) Explain aguous solution of Na2 CO3 is basic. | 3 |
(b) Show that Fe2+ ion acts as oxidant and reduction both. | 2 | |
5. | (a) Describe the shape of given molcule NH3, Pcl5, Bcl3. | 3 |
(b) " Alcl3 exists as Al2 Cl6 at low temperature"- explain. | 2 | |
Or, | (a) What is aufbau principle. Discuss with example. | 3 |
(b) Why inert gases are inert? | 2 | |
6. | (a) A reversible reaction is endless" - Why? explain. | 3 |
(b) Write two uses of Helium. | 2 |
Or | (a) Which one is more covalent and why between CaCl2 and AlCl3. | 3 |
(b) What do you men by STP and SATP? | 2 | |
7. | (a) Write the significance of molar gas constant 'R'. | 3 |
(b) What is meant by isotherm and isopress. | 2 | |
Or, | (a) What is paules' exclusion principle? Write with example. | 3 |
(b) What is diagonal relationship. | 2 | |
8. | (a) Write down three differences between valence and oxidation number. | 3 |
(b) Complete the following reaction. | 2 | |
 (i)  ? +   (ii)    | ||
Or, | (a) Write three major defferences between order of reaction and molecularity of reaction. | 3 |
(b) What is salt bridge of a cell? What is it's function? | ||
9. | (a) Why the heat of neutratization of NaoH and HF is geater then 57.3 kj/male? | 3 |
(b) What is Boltzman constant. | 2 | |
Or, | (a) Write three defferences between electron affinity and electronegativity. | 3 |
(b) Using quantum number calculate the total number of electron in 3rd energy level. | 2 |
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