CBSE Class 12 Chemistry Sample paper 2017 Solved Set A

1. Define Kraft temperature. 

2. The electronic configuration of a transition element in +3 oxidation state is [Ar]3d⁷. Find out its atomic number.

3. Draw the structure of 4-tertbutyl-3-iodoheptane.

4. Give the equation of reaction for the preparation of phenol from cumene. 

5. Name the type of semiconductor obtained when silicon is doped with boron.

6. The two complexes of nickel, [Ni(CN)4]²- and [Ni(CO)₄], have different structures but possess same magnetic behaviour. Explain.

OR

A chloride of fourth group cation in qualitative analysis gives a green coloured complex [A] in aqueous solution which when treated with ethane –1, 2 – diamine (en) gives pale - yellow solution [B] which on subsequent addition of ethane –1, 2 – diamine turns to blue/purple [C] and finally to violet [D]. Write the structures of complexes [A], [B], [C] and [D].

7. Account for the following :

(i) XeF₂ is linear molecule without a bend.

(ii) The electron gain enthalpy with negative sign for fluorine is less than that of chlorine, still fluorine is a stronger oxidizing agent than chlorine.

8. Derive the relationship between relative lowering of vapour pressure and mole fraction of the volatile liquid. 

9. After 24 hrs, only 0.125 gm out of the initial quantity of 1 gm of a radioactive isotope remains behind. What is its half life period?

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