Chem 113 -final 2002

(B. Sc. Biochemistry) First Semester 2002 Subject: Chem 113 (Inorganic chemistry)

Full Marks: 100 Pass Marks: 45 Time: 3 hours

Candidates are required to give their answers in their own words as far as practicable. The figure in the margin indicates full marks. Group (A) Long Questions (Any three)

(3× ×14 = 42)

Group (B) Short Questions: (Any six)

(6× ×7 = 42)

1. What is LCAO approximation? Discuss any two possible combinations of orbitals. 2. What is a metallic bond? Name the crystal structure of metals and explain any two of it. 3. What is crown ether and what is a crypt? Draw examples of group 1st complexes with these molecules. In what way type of complex has biological importance. 4. What do you mean by ionization potential? Discuss the ionization potential along the group and period in case of transition elements.

1. What is a covalent bond? Explain the valence bond theory with examples. 2. Describe how MO theory can be used in heteronuclear diatomic molecules with only one example. 3. Use the band theory to wxplain the difference between conductors, insulators and semiconductors. 4. Why are group I elements: (i) Univalent (ii) Largely ionic (iii) strong reducing agents (iv) Poor complexing agents (v) Why do they have lowest first ionization energy values in their periods? 5. The atomic radius for lithium is 1.23 Å. When the outermost 2s electron is ionized off, the ionic radius of Li is 0.76 Å. Assuming that the difference in radii relates to the space occupied the 2s electron, calculate what percentage of the volume of the lithium atom is occupied by the single valence electron. Is this assumption fair? 6. Transition metal compounds are generally coloured. Explain. 7. Describe the Sidgwick theory of co-ordination compounds. 8. Which of the alkali metal halides are stable on moving down a group?

Group (C) Very Short Questions: (Any eight)

1. What is electronegativity? 2. Why ionic compounds have high melting points? 3. What are stoichiometric compounds? 4. What is the oxidation number of metal in each of the following complex? i. [CO (NH3)6]Cl3 ii. [Fe (CN)6]3

(2× ×8 = 16)

5. Discuss the low melting and boiling point of alkali metals. 6. Why alkali metals are lighter than water? 7. Compounds of alkali metals are colorless but some compounds like K2Cr2O7, KMnO4, Na2CrO4 etc. are colored. Why? 8. Write the three names and uses of catalysts. 9. Transition metals are less electropositive than s block elements. Explain. 10. Why Cu2+ ions are colored but Zn2+ ions are colorless and diamagnetic. Explain. 11. Potassium is more reactive than sodium. Why? 12. Draw the shape of various d-orbitals.