CHEMISTRY TEST (Ch – 1,2,3,4,5& 8) class XII

A.      Answer the following (ANY FIVE) 2 x 5 =10

1.       What is the F.P of 0.1 molal urea solution? (Kf of water 1.86 K kg mol^-1 )

2.       Osmotic pressure of an aqueous solution of KNO₃ is approximately double than that of theoretical value. Explain.

3.       Why AlCl₃ is more effective than KCl in coagulation of Fe(OH)₃ solution?

4.       Write down the difference between lyophilic and lyophobic colloids

5.       When urea is added to the water the freezing point decreases. Explain why

6.       Define heterogenous catalyst with example.

7.       Write two differences between ideal and non-idea solution.

8.       What do you mean by gold no. of starch 20-25.

B. Answer the following question (ANY NINE) 3 x 9 = 27

1.       A metal form cubic close packing. If the atomic radius and density of metal is 1.43Å and 2.7gcm^-3 respectively, then determine the atomic mass of that metal.

2.       What is F- centre? what type of defect exhibit by the following compound NaCl, AgCl, ZnS and CsCl.

3.       The amount of electricity deposit 10g Ag at electrode from aqueous solution of AgNO₃. If same amount of electricity deposit 6.08g gold at electrode form a solution of gold salt. Determine the charge of gold in that solution.

4.       Why magnetic moment of f- block element is higher than d- block element having same no. of un paired electron.

5.       What do you mean by the anisotropic property of a crystalline solid? Potassium crystal is of bcc type and the distance between the two nearest particle is 4.52 Å. What will be its density? (K=39)

6.       Define specific conductivity. A current of 35 ampere is passed through acidulated water for 5min 50sec. how many grams of hydrogen is liberated at cathode?

7.       State Rault’s law related to vapour pressure of the solution of non-volatile solute. What will be the ΔH_mixing and ΔV_mixing for an ideal solution.

8.       When 0.841 NaCl solution is added to red blood cells, it does not shrink or swell-explain the observation. The freezing point is decreased by 0.037 ^oC when 0.684g sugar (M = 342) is dissolved in 100g H₂O. calculate k_f  of water.

9.       What is gold no. what is aerosol? What is meant by coagulation of a colloidal solution? Name any method by which coagulation of lyophobic sols can be carried out.

10.   Write two differences between Schottky and Frenkel defect. What is the total no of particle in bcc lattice. What is salt bridge? Give its two functions.

11.   Define cell constant of a conductivity cell. What is its SI unit. What change will occur if resistance of electrolytes if its temperature is increased.

12.   Calculate emf of the cell

Zn / Zn²⁺ (0.1M) II Cu²⁺ (0.01M) /Cu

Given  ${E^o}_{Zn^{+2}/Zn} \ = -0.76V$   ${E^o}_{Cu^{+2}/Cu} \ = 0.34V$

Write down Kohlrausch law of independent migration of ions

13.  What is osmotic pressure? State henry’s law relating solubility of gas in liquid.

C.    Answer the following question. (ANY THREE) (5 x 3 = 15)

1)    (i) Deduce the integrated form of rate equation of first order reaction.

(ii) what do you mean by activation energy.

(iii) what is pseudo first order reaction.

2)    (i) Show that the half-life period of a first order reaction is independent of the initial concentration of the reactant.

(ii) The rate equation for the chemical reaction:

aA+bB+cC→eE+fF is expressed as -

rate =k[A]α[B]β[C]0

Determine overall order and molecularity of the reaction.

3)    (i) In a multi-step chemical reaction, which elementary step is considered as the rate determining step?

(ii) How does catalyst enhance the rate of chemical reaction.

(iii) According to collision theory of reaction, why all molecular collision does not result in effective collision.

4)    (i) What is activation energy? Write the Arrhenius equation. (ii) If the temperature is increased from 27°C to 37°C for a reaction, the rate constant of that reaction is increased by two times. Calculate the activation energy of the above reaction

5)    Show that the time taken for 99% completion of a first order reaction is twice then the time taken for 90% completion of the same reaction.

D.    Answer the following  ANY FOUR (1 x 4 = 4)

1.    Which point defect in crystals does not alter the density of the solid?

2.    What type of semiconductor is obtained when silicon is doped with arsenic?

3.    What is meant by ‘reverse osmosis’?

4.    Define fuel cell.

5.    Define the term ‘Tyndall effect’

6.  Define ‘electrophoresis’.