Chemistry-78.Phase-5-Subjective

FACULTY TRAINING TEST PHASE - V CHEMISTRY Time: 2 Hours Maximum Marks: 100 Instructions: 1. This paper consists of THIRTEEN QUESTIONS only. 2. Attempt ALL questions. 3. Use of Calculator is NOT PERMITTED Name : 00000000000000000 Subject : 00000000000 1. a) Write the chemical reactions associated with the brown ring test’ b) Draw the structures of [Co(NH3)6]3+, [Ni(CN)4]2– and [Ni(CO)4]. Write the hybridisation of atomic orbitals of the transition metal in each case. c) An aqueous blue coloured solution of a transition metal sulphate reacts with H2S in acidic medium to give a black precipitate A, which is insoluble in warm aqueous solution of KOH. The blue solution on treatment with KI in weakly acidic medium, turns yellow and produces a white precipitate B. Identify the transition metal ion. Write the chemical reactions involved in the formation of A and B. [3 + 5 + 4] 2. a) (i) Write the chemical reactions involved in the extraction of metallic silver from argentite. (ii) Write the balanced chemical equation for developing photographic films. b) Write the chemical reactions associated with the ‘borax bead test’ of cobalt (II) oxide. c) Draw the molecular structures of XeF2, XeF4 and XeO2F2, indicating the location of lone pair(s) of electrons. [3 + 3 + 3] 3. a) The reaction potential diagram for Cu in acid solution is Calculate x. Does Cu+ disporportionate in the solution? Given explanation in support of your answer. [3 + 1 + 4] b) A graph of plotted between Ecell and log10 . The curve was linear with intercept on Ecell axis equal to 1.1V. Calculate Ecell for . [4] 4. Give reason(s) why elemental nitrogen exists as a diatomic molecule whereas elemental phosphorous is a .tetraatomic molecule. [4] 5. Compound X on reduction with LiAlH4 gives a hydride Y containing 21.72% hydrogen along with other products. The compound Y reacts with air explosively resulting in boron trioxide. Identify X and Y. Give balanced reactions involved in the formation of Y and its reaction with air. Draw the structure of Y. [5] `6. A metal complex having composition Cr(NH3)4Cl2Br has been isolated in two forms A and B. The form A reacts with AgNO3 to give a white precipitate readily soluble in dilute aqueous ammonia, whereas B gives a pale yellow precipitate soluble in concentrated ammonia. Write the formula of A and B and state the hybridisation of chromium in each. Calculate their magnetic moments (spin - only value). [6] 7. Starting from SiCl4, prepare the following in steps not exceeding the number given in parentheses (give reactions only): (i) Silicon (1), (ii) linear silicone containing methyl groups only (4), (iii) Na2SiO3 (3) [6] 8. A white substance A reacts with dilute H2SO4 to produce a colourless gas B and a colourless solution C. The reaction between B and acidified K2Cr2O solution produces a green solution and a slightly coloured precipitate D. The substance D burns in air to produce a gas E which reacts with B to yield D and a colouress liquid. Anhydrous copper sulphate is turned blue on addition of this colourless liquid. Addition of aqueous NH3 or NaOH to C produces first a precipitate which dissolves in the excess of the respective reagent to produce a clear solution in each case. Identify A, B, C, D and E. Write the equation of the reactions involved. [10] 9. An orange solid (A) on heating gives a green residue (B), a colourless gas (C) and water vapour. The dry gas (C) on passing over heated Mg gave a white solid (D). (D) on reaction with water gave a gas (E) which formed dense white fumes with HCl. Identify (A) to (E) giving reactions. [8] 10. A certain metal (A) is boiled in dilute nitric acid to give a salt (B) and an oxide of nitrogen (C). A aqueous solution of (B) with brine gives a precipitate (D) which is soluble in NH4OH. On adding aqueous solution of (B) to hypo solution, a white precipitate (E) is obtained. (E) turns black on standing. Identify (A) to (E). [8] 11. Unit cell length of NaCl is observed to be 0.5627 nm by x-ray diffraction studies. The measured density of NaCl is 2.165 g/cc. Calculate % of missing Na+ and Cl–. [6] 12. a) What current should be passed for 30 minutes through 0.1 M solution of Bi(NO3)3 to have complete deposition of metal from 30 mL solution? [4] b) 5.35 g of a salt ACl (of weak base AOH) is dissolved in 250 ml of solution. The pH of the resultant solution was found to be 4.827. Find the ionic radius of A+ and Cl– if ACl forms CsCl species crystals having density 2.2 g/cc. Given Kb(AOH) 1.8  10–5 , = 0.732 for this unit cell. [6] 13. An aqueous solution containing one mole of HgI2 and two mole of NaI is orange in colour. On addition of excess NaI the solution becomes colourless. The orange colour reappears on subsequent addition of NaOCl. Explain with equations. [4] 6