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## CHEMISTRY PU.C. FIRST YEAR (MIDTERM) ### **PART - A** **9) Which of the following is non-polar in nature?** - a) CO2 - b) HCl - c) NH3 - d) H2O **10) Predict the correct order of extent of repulsion among the following:** - a) bond pair-bond pair > lone pair-bond pair > lone pair-lone pair - b...

## CHEMISTRY PU.C. FIRST YEAR (MIDTERM) ### **PART - A** **9) Which of the following is non-polar in nature?** - a) CO2 - b) HCl - c) NH3 - d) H2O **10) Predict the correct order of extent of repulsion among the following:** - a) bond pair-bond pair > lone pair-bond pair > lone pair-lone pair - b) lone pair-bond pair > bond pair-bond pair > lone pair-lone pair - c) lone pair-lone pair > lone pair-bond pair > bond pair-bond pair - d) lone pair-lone pair > bond pair-bond pair > lone pair-bond pair **11) Which of the following statement is correct?** - a) Amount of energy required to break one mole of bond of a particular type between two atoms in gaseous state is called bond enthalpy - b) The unit of bond enthalpy is kJ mol-1 - c) Larger the bond dissociation enthalpy stronger will be the bond in the molecule - d) all of these **12) Which property of carbon is responsible for the formation of large number of carbon compounds?** - a) Catenation - b) Isomerism - c) Tetravalency - d) all of these **13) Pent-2-ene contains** - a) 15 sigma and one pi bond - b) 14 sigma and one pi bond - c) 15 sigma and two pi bonds - d) 14 sigma and two pi bonds **14) What is IUPAC name of the following compounds?** - a) 2-methyl hexan-4-ol - b) 5-methyl hexan-3-ol - c) 2-methyl, 4-hydroxyhexane - d) 5-methyl, 3-hydroxyhexane **15) Fractional distillation is used when** - a) There is large difference in the boiling points of liquids - b) There is small difference in the boiling points of liquids - c) Boiling points of liquids are same - d) Liquids form constant boiling mixture. ### **PART - B** **III. Answer any FIVE of the following. Each question carries two marks. ** **21) The following data are obtained when dinitrogen and dioxygen reacts together to from different compounds:** - Mass of dinitrogen: 14g 14g - Mass of dioxygen: 16g 32g **Which law of chemical combination is obeyed by the above experimental data? Give its statement** **22) State Pauli's exclusion principle** **23) What are isoelectronic species? Give examples** **24) *In terms of period and group where would you locate the elements with Z = 1*a 14?** **25) Write the Lewis symbol for O, and CO2** **26) What is polar covalent bond? Give an example** **27) Give the difference between inductive effect and resonance effect** **28) Write the structural formulas of the following compounds** - a) 3, 4- 4, 5-tetramethylheptane - b) 2-ethylbut-1-ene **29) What is the chain isomerism? Give an example** ### **PART - C** **IV. Answer any THREE of the following Each question carries three marks** **30) a) How does ionization enthalpy varies down the group in periodic table? Give reason** **b) State Modern periodic law.** **31) a) Radius of Na+ is smaller than sodium atom. Why?** **b) Give the IUPAC name of an element with atomic number: 110.** **32) Explain the shape of water molecule using VSEPR theory.** **33) Give the difference between sigma bond and pi bond** **34) Explain sp3 hybridization by taking BCl3 as example** ### **PART - D** **V. Answer any THREE of the following. Each question carries three marks.** **35) a) What is Heterogeneous mixture? Give an example** - b) Express 0.0048 in scientific notation. **36) a) Define (I) mole, (II) molar mass** **b) What is molar mass of sodium chloride.** **37) Give any three Characteristics of Cathode rays.** **38) a) Give any two limitations (drawbacks) of Rutherford atomic model** - b) Write the unit of wave number **39) Give any three postulates of Bohr's atomic model.** **40) Write the significance of three quantum numbers?**