MODEL SECONDARY SCHOOL FIRST TERMINAL EXAMINATION-2079 dANAKPUR-O4 s Subject: Chemistry FM: 75 -| Class: XI (Science) Time: 3Hrs. P.M. 27 | Group (A’ P | Attempt all questions. | “Write the best alternative to the following questions. [11*1=11] 6 : 1. One mol of H2SO4 contains 31 | "4 64gofO — b.6.023 x 10%molccules 62.016 gofH dall 2. Lamuis equal to 2. 1.6610" gram —b. 1.66«107%kg_ —o. /Na gram all 3. The simplest pure form of matter which is composed from two or more pare than two atoms in the fixed ratio by their mass is known as.—~ aan 1 a. element be compound c, mixture d. atom ™ 4, One mol of an atom is equal to 2 a. tg atom b.aiomic mass of an atom ¢.6.023x10" atoms 4. all 5. Which one of the following is metalloids? a, Na b. Zn eC a Sb 6. The reagent which is used up first in the chemical reaction is known as a. Limiting reagent b. excess reagent e c. oxidizing agent d. reducing agent . 7. Oxidation number of Cr in CrOs is “ a. +8 b.+6 S10 d.+4 8. Fluorine has less electron affinity than that of a. Na b. Cl c, Oxygen «a Mg 4 9. In periodic table elements having same valence shell electronic is a configuration are placed in , ¥ | a. the different groups _b, the same group _. any where d. none t | 10. Which one of the following is not a redox reaction ? I | a. Mg+Cl, = MgCh b. 4Na + O2 > 2Na20 ¢, NaOH(aq.+HCi(aq.) > NaCi(aq) +H20(1) gC + Or CO2 11. Which one of the following statement is not correct for the element having electronic configuration 13°2s?2p°3s' 2 p-Itis monovalent & electropositive b. It forms basic oxide | c, It is metal 7 d. Having high 1.P. value——_ , j Group (B) Give short answer to the following questions. [8x5=40] 12. What is molecular formula? Write the molecular formula of sodium zincate and sodium acetate, What are the significances of the molecular formula? [24142] Or, ‘on 8 _ feisty State Jaw of mass action. Show that Ke = are What is the relationship between K, and Ke. [2+2+1] 13. Define mole. Calculate the no. of each atoms present in 9.8 gram of ‘H3PO,.What mass of Zn will contain the same number of atoms as are Present in 2.4 gram of Mg? [1+242) Or, a. Show that molecular mass = 2x V.D. [2) b. Show that all the elementry gases are diatomic. (2) ¢ Phosphorous forms P203 & P20s with oxygen. Show that these data illustrate the law of multiple proportion. 1] 14. (a).3.42 gram of sucrose(Ci2H220,)) is dissolved into 180 gram of / water(H20).Calculate the no.of oxygen atoms in the solution. [2] (b.) Calculate the no.of electrons present in 1.7 gram of NHs. [2] (c) Define atomic mass unit. Ql 15. Calculate the molecular mass of the followings: [5x1=5] i, Na2CO3.10H2@ ii. HNOs iii. CuSOs.5H20 iv. C)Hs0H v. CaCO; Or, Hydrogen atom contains single electron but it gives rise to hydrogen spectrum. Explain. 6 A . ay 16. a. Define: (i) oxidation and reduction in terms of oxidation number with / 7 example. 2] J (ii) auto-redox reaction 7 b. Show that given reaction is a redox reaction. Q) , Mg(s) + Clh(g) = MgCh(s) § 17. Calculate the oxidation number in the following: . EA ‘ (a) Cr in KxCr,07 (b) Mn in KMn0, (c) Cl in CaOCl, = (@)NinNH,; — (c) Nin HNO, (5«1=5] Wax as or, The periodic table is a chart present in every chemistry lab and classroom in the world, showing the elements arranged in increasing order of atomic number. aSt b.W give Giv 20. PRP Tegroup, period and outermost a, Complete the given table indicating electronic configuration. 2] Element Group Period Outermost —}\ Ec. Oxygen VIA a 2572p" Magnesium Potassium Chlorine J ; a 7 py - b. Which one has greater ionization potential and why ? N or O. c. Give one factor that influences ionization energy. ft) 2 18. {a) What are the differences between strong electrolyte and weak ies electrolyte? [2] . (b) State and explain Faraday's second law of electrolysis. [3] ne 19, Complete the table to show the number of electrons, protens-and~ SY. neutrons in the sulfur atom and iron shown in the given table. [2] Symbol ‘Number of Number of Number of electron proton neutron *Si6 * Fens 26 I ‘@.Siate Modem periodic law? fi) b.Why does first ionization energy itjorbases from lefi to right in the given period of the periodic table? [2] Group (C) a) Give long answer to the following questions. [3x8=24) V Pr! 20. In the lab preparation of carbon dioxide CaCO; +dilLHCl > CaCh(aq.) + H2O()) +COx(g) If 10 gram of CaCO; is treated with 7.65 gram of dil-HCI then a a.Which one will be the limiting reagent and why ? (7 * sy b. Calculate the no.of moles of the excess of the reagent left over unreacted. [2] we O° c. Calculate the masses of CaCl, formed in the reaction. fy & d, Calculate the volume of CO gas evolved at NTP ? Q] e, Calculate the masses of aq.NaOH required to absorb whole of the CO) formed in the reaction. [2] a =a 21. What is oxidation number ? Inthe given chemical reaction KMnOy+HCl—> KCl + MnCh +H20 + Ch | Which one will be the oxidising and reducing agent ? Justify it. Balance the above equation by either oxidation number method or ion electron method . [2+2+4] 22. (a) Mass number is always whole number but atomic mass is “ fractional, why? (2) (b) Define relative atomic mass and relative molecular mass with | respect to C-12 isotopes. (3) (c) Calculate the no. of gram equivalent in the followings: [3*1=3] (i) 3.5 g of HCI (ii) 10 g of CaCOs (c) 4 g of NaOH Or, In the manufacture of NH3 gas by Haber’s process _. 3H.(g) + Na(g) == 2NHs + heat What is the effect of change in concentration, temperature and pressure i on the equilibrium stage? State Le- Chatellier's principle. Chemical / equilibrium is dynamic in nature.why? [ori+1} Best of luck*** | { / ( : | yt