CHEMISTRY PAPER

JAWAHAR NAVODAYA VIDYALAYA AMARKANTAK ANUPPUR M.P. UNIT TEST NO. 2 CLASS XII SUBJECT : CHEMISTRY (THEORY) TIME: 2 HR M.M. 50 Roll No. ________ INSTRUCTION: 1. Question Paper consist of Q No. 1-10 (1 Mark), Q.No.11-20 (2 Mark), Q. No. 21-25 ( 3 Marks) 26 (5 Marks) 2. Sub Instrucctions are given in each section. 3. Provide proper diagram if needed. Give one example of oil in water and water in oil emulsion? Give one example of enzyme catalyzed reactions? What is demulsification? Name two demulsifiers? Which method of refining is generally used when metal of high degree of purity is needed? How does NaCN act as a depressant in preventing ZnS from forming the froth? What is composition of Copper matte? Why ICl is reactive in comparision to I2? Why Flourine is strong oxidizing agent in comparison to Chlorine, inspite of lower Electron Gain Enthalpy? NCl3 is readily hydrolysed whereas NF3 does not? Why PCl5 readily decomposes to PCl3 and Cl2? Write difference b/w Physical and Chemical adsorption with example? Explain the following term: Tyndall Effect b. Electrophoresis The value of fGo for formation of Cr2O3 is -540 kJ mol-1 and that of Al2O3 is -827 kJ mol-1 Is reduction of Cr2O3 is possible with Al? Write the reaction of White Phosphorous with: NaOH b. Chlorine Explain the preparation of XeF2 with its structure? Arrange the following on the basis of property indicated: Hydrides of Group 15 – increasing basic character Oxy acids of Group 17 – increasing acidic strength Why: Water has higher boiling point than H2S NH3 is most stable hydride of 15 group element Discuss four anomalous property of Nitrogen? Write the different oxyacids of Sulfur with their basicity? Write two uses of : i. Helium ii Argon Explain what happens when: Beam of light is passed through colloidal solution of As2S3 Sodium Chloride is added to ferric hydroxide sol An electric current is passed through colloidal solution Write short note on: Calcination c. Van Arkel Method Mond’s Process Draw the structure of following (with Hybridization involved) XeF6 b. BrF3 c. XeO3 a/ SF6 is known but SCl6 unknown Sulphur is paramagnetic in vapor phase Nitrous acid act as both oxidizing and reducing agent. Justify the placement of O,S,Se, Te and Po in the same group of the periodic table in terms of electronic configuration, oxidation state and hydride formation? i. Explain Why: Halogens are strong oxidizing agent Nitrogen found as diatomic whereas Phosphorous P4 O3 act as a powerful oxidizing agent ii. What are inter halogen compounds Or// Explain Why: Bond angle in PH4+1 is higher than that in PH3 Pentahalides are more covalent than trihalides Compounds of Xenon are possible How can O3 estimated