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Chemistry Class - XII 1997 (CBSE)
You are on
questions 1 to 20 of Set I
Q.1 State the physical significance of  2. (1 mark)
Q.2 Write which one out of
O+2 and O--2 is more stable?
(1 mark)
Q.3 Write an expression in the form of a chemical
equation for standard enthalpy of formation of for CO? (1
mark)
Q.4 Write an expression to relate molar
conductivity of an electrotype to its degree of dissociation? (1
mark)
Q.5 What is the 'ambident group' ? Give an example.
(1 mark)
Q.6 Indicate a chemical reaction involving a
homogeneous catalyst ? (1 mark)
Q.7 Mention two main function of carbohydrates in
plants ? (1 mark)
Q.8 How many sigma bonds are present in
3-methylphenol ?(1 mark)
Q.9 Mention the chief reason for the resemblance
between beryllium and aluminium ? (1 mark)
Q.10 Mention two important uses of sulphuric acid ?
(1 mark)
Q.11 What is energetically achieved by coupling
reaction in biological system? Explain. (1 mark)
Q.12 What types of substance generally constitute a
chemical propellant? Briefly describe the function of rocket propellant.
(2 marks)
Q.13 The ionisation energy of hydrogen atom is
1.312x106 J mol-1. Calculate the energy required to
excite the electron in a hydrogen atom from the ground state to the first
excited state. (Avagadro constant=6.022x1023
mol-1)
(2 marks)
Q.14 Describe briefly two important function of
nucleic acid. (2 marks)
Q.15 Calculate the free energy change when one mole
of sodium chloride is dissolve in water at 298K.
(Given : Lattice
energy of NaCl= -777.8 kj mol-1, Hydration energy of NaCl=
-774.1kj mol-1 and  S at 298 K = 0.043
K-1mol-1. (1 mark)
Q.16 For the equilibrium PCl5(g)
<===> PCl5(g) + Cl2(g) at 298 K,
K=1.8x10-7. Calculate Go for the reaction.
(R=8.314JK-1mol-1). (1 mark)
Q.17 The freezing point of pure nitrobenzene is
278.8 K. When 2.5gm of an unknown substance is dissolve in 100gm of
nitrobenzene, the freezing point of the solution is found to be 276.8K. If
the freezing point depression constant of nitrobenzene is 8.0K Kg
mol-1, what is the molar mass of unknown substance? (2
marks)
Q.18 For the reaction, 2A+2B+C----->
A2B+C, rate law has been determined to be: rate =
k[A][B]2. If the rate constant, k = 2.0x10-6
mol-6L2 and [C]=0.8 mol L-1? (2
marks)
Q.19 For the reaction NO2(g)+
CO(g)----->CO2(g) + NO(g) the
approximately determined rate expression below 400K is rate =
k[NO]2 what mechanism can be proposed for above reaction. (2
marks)
Q.20 write IUPAC name of the following compounds
:
(i)
(CH3)3C.CH2.CH2Cl
(ii)
CH3.CH.CH.CH.CHO (2 marks)
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