Chem 113 -internal 2002

Universal Science College (B. Sc. Biochemistry) First Semester 2002 Second Term Exam Subject: Inorganic Chemistry Date: 19 Jan, 2003

Full Marks: 100 Pass Marks: 50 Time: 3 hours Group - A

Answer any three questions. Questions are of equal value. 3 × 14=42 1. What is LCAO approximation? Discuss any two possible combinations of orbitals. 2. Explain the term lattice energy as applied to an ionic solid. Write down the Born-Lande equation and define the terms in it. 3. By studying the complexes by molar conductivities measurement, how will you relate the modern and Werner’s structure of CoCl3. 6NH3 and CoCl3 .5NH3. 4. How do the following properties vary in the transition elements? i) ionic character ii) stability of various oxidation states iii) ability to form complexes iv) lowest oxides are basic whereas the highest oxides are usually acidic. Group B Answer any six questions. Questions are of equal value. 6 × 7 = 42 1. What is hybridization? Define the three types of hybrid orbitals that may be formed by an atom with only s and p orbitals in its valence shell. 2. Draw shapes of the various d-orbital and explain why they are split into two groups t2g and eg in an octahedral field. 3. Use the MO theory to predict the bond order and the number of unpaired electrons in O2 and O2 –2 4. Explain the structure of chlorine trifluoride using valence shell electron pair theory (VSEPR). 5. Define the following terms and give one example of each. i. Complex ion ii. Bi-dentate ligand iii. Co-ordination number iv. Co-ordination sphere 6. AlCl3 is covalent in anhydrous form but it forms metal ion in solution. Explain. 7. Why are the group 1st metals soft, low melting point and of low density? 8. What do you mean by d-d transition? Explain with examples. Group – C Answer any eight questions. Questions are of equal value. 1. What is electronegativity? 2. Why covalent compounds are insulator? 3. What is Hund’s rule? 4. Why diamond and SiO2 have high melting points? 5. Name possible crystal structures of metals. 6. Why ionic compounds have high melting points?

8 × 2 = 16

7. 8. 9. 10. 11. 12.

What do you mean by outer-orbital complex? Write down the formula of copper complex which gives deep blue color in solution and also determine the oxidation state of central metal ion. Name the structure of which has B12 unit of Boron in solid state. Mention how many allotropic forms are there in Boron. Cupric salts are blue in color while cuprous salts are colorless. Why? Calculate the magnetic moment of Cu2+, Co2+ and Fe3+ ions. Alkali metals do not form dipositive ions. Explain. ***