Chemistry – Important Questions Bank for Karnataka HSC 2016 Examination

1.A) In the preparation of m-dinitrobenzene form nitro benzene-

. Name the regents used

. Write the chemical equation for the reaction

. What is the color of the product?

B) Give the general chemical test for carbohydrates.

2.) For the estimation of ferrous ammonia sulphate using standard potassium dichromate solution-

. Write the chemical equation for the reaction involved

. Give equivalent mass of ferrous ammonia sulphate

. Name the indicator used.

. What is the color change at the end point?

3. Describe the experiment to determine the effect of temperature on the rate of the reaction between potassium persulphate and potassium iodide. What is the conclusion drawn from the experiment?

4. For the estimation of potassium permanganate using standard oxalic acid solution

. Write the chemical equation for the reaction involved.

. Give the equivalent mass of potassium permanganate.

. Name the indicator used.

. Write the color change at the end point.

. Write the equation for calculating the mass of potassium permanganate present in 250 cm ³ of the solution from its normality.

5.  For the estimation of Mohr’s salt using standard potassium dichromate solution:

. Write the chemical equivalent mass of Mohr’s salt.

. Name the indicator used.

. What is the color changes at the end point of the titration?

. Write the formula for calculating mass/dm ₃ of Mohr’s salt in the given solution from its normality.

6. Define the term ‘half-life period’. Show that the half-life period of a first order reaction is independent of initial concentration of the reactant.

7.  Calculate the standard free energy change of a cell prepared by combining Zn| Zn ⁺² and Mg | Mg ⁺² electrodes at 298 K.

(Given : E ^˚_Zn = – 0.76 V ; E˚ _Mg = – 2.37 V)

8. A)  How would you convert acetic acid to methane? Give the equations.

B) Give any three salient features of molecular orbital theory.

9. A) Explain the construction and working of standard hydrogen electrode. Give on limitation of it.

B) Explain with equation, the role of limestone in the extraction of iron form haematitie ore.

C) Define the following:

. Chirality Centre

. Geometrical isomerism.

D) Carbohydrate is a source of energy. Explain

10.  A) Draw a neat diagram of blast furnace for the extraction of iron from hematite. Write the reactions taking place in (i) reduction zone and (ii) slag zone of the furncace mentioning the respective temperatures.

b) Calculate the pH of a buffer solution containing 0.2 mole of potassium format and 0.3 mole of formic acid per dm 3 of the solution.

(K _a for formic acid is 1.75 x 10 ^{– 4})

c) Explain the steps involved in the mechanism of hydrolysis of tertiary butyl bromide using aqueous potassium hydroxide.

d) Write the general equations for the reactions of an aldehyde with (i) HCN, (ii) Hydrazine.

11. A) With the help of V B T, explain the hybridization in tetra carbonyl nickel (O) and sketch the shape of the complex.

b) The rate constants of a first order reaction at 300 K and 310 K are respectively 1.2 x 10 ³ s ^{– 1} and 2.4 x 10 ^{– 3} s ^{– 1} Calculate the energy of activation

( R = 8.314 JK ^{– 1} mol ^{– 1})

c) Give one reaction each to show that

1. a benzene ring contains three double bonds
2. all the six hydrogen atoms in benzene are chemically equivalent

d) Explain with an example, Clemmensen reduction.

12. a) Explain the construction and working of standard hydrogen electrode.

b) Explain S _N 2 mechanism with an example

c) Write the general outermost electronic configuration of 3 d – series of elements. Hence explain.

1. Why Zn ^{+ 2} ion and Sc ^{+ 3} ion are colorless
2. Ti ^{+ 3} ion is paramagnetic.

13. a) State Raoult’s law of relative lowering of vapor pressure. Give the mathematical form of it.

b) Energy of activation of a first order reaction is 56.6 K^J / mol. If its rate constant at 298 K is 2.4 x 10 ^{– 3}/ min, calculate the rate of constant at 308 K. (R = 8.314 J/K/ mol.)

14. a)  What is an elector chemical series? Give one application of it.

b) Calculate the hydrogen ion concentration of a solution whose pH is 5.6.

c) Write the conjugate base of HCO  ₃ ^-1

15.  a) What is standard free energy change of a chemical reaction ? How it is related to the equilibrium constant?

b) How is gold sol prepared by Bredg’s electric are method?

c) Give an example for molecular crystals.

16. a) A first order reaction takes 30 minutes for 60% reaction to be complete. What is the rate constant of the reaction?

b) Calculate the time required to liberate 112 cm 3 of hydrogen at STP. If 5 amperes current flows through the acidified water.

17. Calculate entropy change taking place when 1 Kg of ice melts at 0˚ C

( Δ H _fusion  = 6.0285 KJ/mol)

18. Describe Ostwald-Walker method of measuring the relative lowering of vapor pressure.

19. Define gold number

20. a) Mention any three limitations of standard hydrogen electrode

b) Write Arrhenius equation and explain the notations.

21. a) Explain why II and JV group basic radicals are precipitated as their sulphides in acidic and basic mediums respectively.

b) Sketch the unit cell structure of Ceasium chloride., what is the co-ordination number of each ion in the crystal?

22. a) The vapor pressure of a solution containing 10 g of a non- electrolyte in 200 g of water at a particular temperature is 2985 Pa. The vapor pressure of pure water at that temperature is 3000 Pa. Calculate the molecular mass of the solute

b) How do you show that ammonia acts both as a a Lewis base and as a Bronsted base?

23. What are lyohilic and Iylphobic sols? Give one example for each

24. Zinc liberates hydrogen gas from dilute sulphuric acid but copper does not. Why?

25. Solubility product of silver chloride is 1.7 x 10 – 10 at 298 K. calculate is solubility at the temperature.

26.  state Nernst distribution law.

27. Explain Reimer-Thiemann reaction with an example

28. Give any two differences between mesomeric and inductive effects.

29. Many transition metals and their compounds are used as catalysts in several chemical reactions. Why?

30. How does electron gas theory explain the malleability and ductility of metals?

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