Chemistry-5.ITS-Half Course Test-1-Questions

HALF COURSE TEST - I (MAILING) CHEMISTRY Time: Two Hours Maximum Marks : 100 Note: i) This paper has TEN questions. ii) Separate answers are to be given on the separate pages. iii) Attempt all questions. iv) Use of logarithmic table is PERMITTED v) Use of calculator is NOT PERMITTED Useful Data: Gas Constant R = 8.314 J mol−1 K−1 = 0.0821 lit atm mol−1 K−1 = 2 Cal mol−1 Avogadro's Number Na = 6.023 × 1023 \Planck’s constant h = 6.625 × 10−34 J sec. 1 Faraday = 96500 Coulomb 1 calorie = 4.2 Joule Atomic No: Ca = 20, C = 6, O = 8, K = 19, Cl = 17, N = 7, S = 16, Na = 11, Cu = 29, Co =27, Mn = 25. Atomic Masses: Ag =108, Mn = 55, Cr = 52, Ca = 40, C = 12, O = 16, K = 39, Cl = 35.5, N = 14, S = 32, Na = 23, H = 1, I = 127, Mg = 24, Ne = 20, Br = 80, I = 127, As = 75, Cu = 63.54 Name : ☐☐☐☐☐☐☐☐☐☐☐☐☐☐☐☐☐ Enrol No. : ☐☐☐☐☐☐☐☐☐☐☐☐☐ 1. A salt M1M2C4H4O6, 2H2O is heated until to get a constant weight. On constant ignition, it is converted into M1M2CO3. After complete burning the resultant solid was treated with 45 ml 0.2 M H2SO4. The resulting mixture was back titrated by 0.1M NaOH. If the volume of the NaOH required for back titration is 2.39ml and initial wt. of the sample is 10.732 gm then calculate the percentage purity of the sample. Consider M1 and M2 are two metals of valency one. Atomic wt. of M1 =23, M2 = 39, C = 12, O = 16. [10] 2. A mixture of CO2, N2 and water vapour is introduced into a flask which contains solid dry CaCl2. Immediately after introduction of the gas mixture the pressure of the flask is observed 765mm. Now the gas mixture is cooled to 0°C. After sometime the pressure reached a steady value 645mm. Then through the gas mixture potassium hydroxide is passed and pressure of the gas falls to 345 mm at 25°C. If the initial temperature of the gas mixture was 35°C, then calculate the composition in mole % of original mixture. Neglect the volume change of the flask. [10] 3. The uncertainty for the calculation of radius of the 1st Bohr orbit is 2% for the hydrogen atom. What will be the uncertainty in velocity of electron in the 1st Bohr orbit. Given mass of an electron = 9.1 × 10–28 gm Charge of an electron (e) = 1.6 × 10–19C εo = 8.854 × 10–12 C2N–1m–2 h = 6.626 × 10–27 erg sec [10] 4. The isotope 71X192 and 71X193 occurs in nature in the ratio of 1:147. Assuming that at the time of earth formation, they were present in equal amount make an estimation of the age of earth. The half life period of X192 is 4.5 × 107 years and that of X193 is 9.3 × 109 years. [10] 5. An equilibrium mixture of CO(g) + H2O(g) CO2(g) + H2(g) present in a vessel of 2 lit. at a temperature 900°C was found to contain 0.4 mole of CO2, 0.3 mole of H2O, 0.2 moles of CO and 0.5 moles of H2. To increase the concentration of CO to 0.4 mole, CO2 was added to the vessel. How many moles of CO2 must be added into equilibrium mixture at the constant temperature in order to get this change? [10] 6. a) Arrange the following compounds in their increasing order of acidity and give the explanation. [4] b) Arrange the following compounds in their increasing order of basicity and give the explanation. [4] 7. Explain the following facts [3 + 4] a) Among the halides of lithium, the melting point of LiF is maximum. b) Bond order of and are same but bond energies are different. 8. a) What are the hybridisations of the central elements into the following species. [1½ + 1½] (i) POCl3 (ii) H2Me b) Give the IUPAC nomenclature of the following compounds: [2 + 2] i) CH3 – CH = CH – C ≡ C – CH3 ii) c) Carry out the following conversion using suitable reagents. [3] 9. a) has two asymmetric centres but the compound is optically inactive – explain. What is the number of stereoisomers of this compound and also predict their optical activity. [2 + 1½ + 2] b) O2N – CH2 – CH = CH2 X [1½ +2½] What is X and explain the formation of X. c) [2] 10. Due to ozonolysis of compound A two compounds B and C are obtained. Compound B also can be obtained from CH4 by heating in presence of O3. Compound C undergoes clemmensen reduction to give compound D which gives a monobromo product E. Compound E undergoes Wurtz reaction to give butane as the major product. Identify A to E. [5 × 1½ = 7½] 11. Balance the following redox reaction with proper explanation. [3 × 2 = 6] a) b) As2S3 + + H+ + H2O ⎯⎯→ H3AsO4 + NO + S 6