CBSE Guess > Papers > Important Questions > Class XII > 2010 > Chemistry > Chemistry By Kaushik

CBSE CLASS XII

Q. 19. A solution contains 30g of non-volatile solute exactly in 90g of water has a v.p of 2.8KPa at 298K. The v.p becomes 2.9 KPa when 18g of more water is added to it. Calculate→

1. Molar mass of solute
2. v.p of water at 298K 

Q. 20.

1. State Faraday’s second law.
2. Write the Nernst equation and calculate emf of the cell→
   Fe(s)/Fe²⁺(0.001 M)// H⁺(1 M)/ H₂(g)(1 bar)/ Pt(s). E^0Fe₂₊/Fe = -0.44V.   1+2= (3)

Q. 21. Give reasons for the following→

1. Enzyme catalysts are highly specific in their action.
2. The path of light becomes visible when it is passed through As₂O₃ sol.

Q. 22. Name one ore of cupper. How is it concentrated? Write all the chemical reactions involved in its extraction.

Q. 23. Explain giving reasons→

1. Transition metals show paramagnetic behavior.
2. Enthalpy of atomization of Zn is lowest in its series.
3. E0Cu²⁺/Cu= positive.

Q. 24.

1. Why does CH₃COOH undergo HVZ reaction?
2. Why formic acid stronger than acetic acid?

Q. 25. Arrange the following in order of property indicated→

1. F, Cl, Br, I→ increasing electron affinity
2. HCl, HBr, HF, HI→ increasing acid strength
3. NH₃, PH3, AsH3, SBH3, BiH3→ increasing basicity. 

Q. 26.

1. Why aryl halides less reactive than alkyl halides towards nucleophilic substitution reaction.
2. In spite of electron withdrawing nature of halogens, still they are o- and p- directing towards electrophilic substitution reaction. Why?

Q. 27.

1. What are anomers? How many anomers of glucose are known? Name thaem.
2. What are essential amino acids? Give one example.

Q. 28.

1. the rate constants of a reaction at 500K and 700K are 0.02s-1 and 0.08s-1. Calculate the value of A and Ea.
2. 
   
   1. Identify the order of reaction in plot.
   2. What is unit of rate constant?
   3. What is slope equal to?
   4. What is intercept equal to?

Q. 29.

1. Why SF6 not hydrolyzed but SF₄ can be?
2. Arrange the following based on oxidizing power→ HOClO₂, HOCl, HOClO, HOClO₃.
3. Draw the structure of the following oxo-acids→ H₂SO₅ , H₂S₂O₈. 

Q. 30.

1. The hydrocarbon A adds one mole of H₂ in presence of Pt catalyst to form  n-hexane. When A is oxidized with KMnO₄, A single carboxylic acid B formed. B when heated with Ca(OH)2 to form calcium salt which on distillation give C. C reacts with HCN to give D. D on hydrolysis in presence of acid form E. Identify A,B,C,D,E and write the reactions involved.
   
   
2. An organic compound A contains C, H, O and Cl. It reduces Fehling’s solution and on oxidation gives a monocarboxylic acid B. B on treatment with soda lime gives a sweet smelling liquid C, which can also be obtained by heating A with alkali. A can also be obtained by the action of Cl₂ with ethyl alcohol, Deduce the structure A, B, C with reactions involved.

Paper By Mr. Kaushik
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Ph No.: 9406830780