Chemistry I

CHEMISTRY-I TIME ALLOWED: 3 HOURS MAXIMUM-MARKS: 100 Note: Attempt FIVE questions in all, including QUESTION NUMBER 8 which is COMPULSORY. All questions carry equal marks. 1. (a) Why do the lines in the atomic spectra more closer with increasing wave lengths? (b) Write Schrodinger’s equation and explain each term involved. (c) Distinguish between the intramolecular and intra-molecular hydrogen bonding. (d) Name any four characteristic properties of metals-and explain them in terms of the theory of metallic bonds. - 2. (a) What do you understand by: (i) reference electrode. (ii) Indicating electrode. (b) Obtain the relationship between the concentration of the electrolyte and e.m.f. of the cell. (c) Why can’t we measure or calculate a system’s internal energy? (d) Will the entropy change for each of the following be positive or negative? (i) Raindrops from a cloud. (ii) Sugar dissolves in coffee. (iii) Air is pumped into a tyre. (iv) Moisture condenses on the out side of a cold glass. (v) Frost forms on the wind shield of a car. 3. Explain with reasons: (a) Oxygen do not show variable oxidation states. (b) Phosphorous has a tendency to form covalent compounds. (c) Nitrogen is less reactive than phosphorous. (d) Carbon is used as the most common reducing agent. 4. (a) Define: (i) Ore (ii) Mineral (iii) Native state (iv) Flux (v) Slag. (b) Discuss the need for the concentration of ores. (c) Mention the method adopted for the concentratiop of the following ores: (i) Bauxite (ii) Silver Glance. (d) Explain the purification of silver metal by Park’s process. 5. Write short notes on: (i) Semi conductors (ii) Varieties of glass (iii) Thin films (iv) Portland cement. 6. (a) What properties of the transition elements are consistent with their being metals? (b) Explain how sigma (s ) and pi (p ) bonding help each other synergestically in stablizing the compound. (c) The dz2 orbital is considered to be the LCAO of two orbitals. Which orbitals are they and how do they combine. (d) Which of the complex ion namely [Fe(CN6)] 3- and [ Fe(OH2] 2+ is an outer orbital complex and why? —

7. (a) What is thermal pollution of water? Is it necessarily undesirable? (b) Distinguish between softening and de-mineralizing of water. Does demineralization soften water? (c) Name the five principal Air pollutants and identify a source of each of these pollutants. (d) Explain how atmospheric ozone prevents pollution COMPULSORY QUESTION 8. Select and write the correct answer only in the answer book. Don’t reproduce the question: (1) An example of an extensive property is: (a) temperature (b) pressure (c) molar volume (d) enthalpy (2) A process in which no heat enters or leaves the system is called:(a) isothermal (b) isobaric (c) adiabatic (d) isochroic (3) A process in which the system, after undergoing various process, returns to its initial state is called a/an: (a) cyclic process (b) irreversible process (c) reversible process (d) Hess’s law (4) A half cell reaction is one that: (a) occurs at one electrode (b) goes only halfway to completion (c) involves a half mole of the concentration of the solution (d) always oxidises. (5) Which of the following statements is not correct regarding galvanic cells? (a) Oxidation occurs at the anode. (b) Ions carry current inside the cell. (c) Electrons flow around the external circuit from cathode to anode. (d) When the e.m.f. of the cell is positive, cell reaction is spontaneous. (6) The spectral line obtained when an electron jumps from n =6 to n= 2 belongs to the: (a) Balmer series (b) Lyman series (c) Paschen series (d) Pfund series

(7) Which of the following transitions of electrons in the hydrogen atom will emit maximum energy? n5 ® n4 ; n4 ® n3 ; n3 ® n2 ; (a) n5 ® n4 (b) n4 ® n4 ® n3 (c) n3 ® n2 (d) Same in all transitions. (8) Which of the following species is diamagnetic? (a) O2+ (b) O2 (c) NO (d) NO+ (9) The weakest bond among the following is: (a) Ionic (b) Covalent (c) Metallic (d) hydrogen bond (10) Bleaching powder reacts with water to give: (a). oxygen (b) chlorine (c) both (d) None of them. (11) The best form of iron is: (a) cast iron (b) wrought iron (c) steel (d) alloy steel (12) Alluminium Oxide is: (a) an amphoteric oxide (b) a basic oxide (c) an acidic oxide (d) none of them (13) Ni(CO)4 is: (a) tetrahedral and dimagnetic (b) tetrahedral and paramagnetic (c) octahedral and dimagnetic (d) octahedral and paramagnetic (14) Yellow phosphorous is soluble in: (a) CO2 (b) CS2 (c) H2O (d) alcohol (15) The Oxide containing chlorine in its highest Oxidation state is: (a) C12O7 (b) C1O3 (c) C1O2 (d) CIO (16) Pi (ir) bonding occurs in each of the following except:

(a) CO2 (b) C2H4 (c) CN (d) C6H6 (17) Which of the following substances is commonly called laughing gas? (a) N2O (b) NO2 (c) NO (d) N2 (18) Which of the following ions is colour less? (a) Cu2+ (aq) (b) Fe3+ (aq) (c) Zn 2+ (aq) (d) Ni2+ (aq) (19) Which of the following element shows metalloid character? (a) Ni (b) Sb (c) Pt (d) In (20) The Oxidation number of N and H in NH4~ ion are: (a) +3, -I (b) +3,+I (c) -3, -I (d) -3,+ I *************************