Test Venue: Lajpat Bhawan, Madhya Marg, Sector 15-B, Chandigarh Dr. Sangeeta Khanna Ph.D 1 CHEMISTRY COACHING CIRCLE G:\Mega Scholarship Test - MEDICAL.doc Dr. Sangeeta Khanna Ph.D READ INSTRUCTIONS CAREFULLY 1. Please mention your Name, Roll No. on the OMR Answer Sheet. 2. Mention/Fill bubbles carefully on your OMR Answer Sheet – Booklet – A, Booklet – B, Booklet – C or Booklet – DB as mentioned on your Question Paper. Otherwise your answer sheet will not get properly evaluated. 3. The test is of 2 hours duration. 4. This test consists of 60 questions. 5. The maximum marks are 180 6. For each question in Section A, B & C you will be awarded 3 marks if you have darkened only the bubble corresponding to the correct answer and zero mark if no bubbles are darkened. Minus one (-1) mark will be awarded for wrong answer 7. Keep Your mobiles switched off during Test in the Halls. Section – A (Single Correct Choice Type) This Section contains 31 multiple choice questions. Each question has four choices A), B), C) and D) out of which ONLY ONE is correct. (Mark only One choice) 31 × 3 = 93 Marks 1. Which of the following statements is incorrect about internal energy? a. b. c. The absolute value of internal energy cannot be determined The internal energy of one mole of a substance is same at any temperature or pressure The measurement of heat change during a reaction by bomb calorimeter is equal to the internal energy change Internal energy is an extensive property d. B Sol. Internal energy of a substance depends upon temperature and pressure. 2. For combustion of 1 mole of benzene at 25°C, the heat of reaction at constant pressure is – 780.9 kcal. What will be the heat of reaction at constant volume? 1 C6H6(( ) 7 O2(g) 6CO 2(g) 3H2O( ) 2 a. – 781.8 kcal b. – 780.0 kcal B Sol. qp = qV + ngRT, qv=qp-ngRT (H=E + ngRT) qv = -780.9 – (- 1.5 × 2 × 298 × 10-3) = - 780 kcal 3. G in the process of melting of ice at -10 °C is c. 781.8 kcal d. 780.0 kcal a. > 0 b. < 0 c. = 0 d. None A Sol. Melting of ice is non-spontaneous at 10°C, so G = +ve 4. In an experiment, NO2 gas is prepared and taken into 3 test tubes X, Y and Z. NO 2 gas which is brown in colour dimerises into N2O4 which is colourless. Test tube X is kept at room temperature, Y is kept in ice and Z is kept in hot water. What colour changes will you observe in the test tubes and why? 2NO 2(g) N2O 4(g) ; H -57.2 kJ mol -1 Brown Colourless Ice NO2 Hot water NO2 X Dr. Sangeeta Khanna Ph.D Y Z 2 CHEMISTRY COACHING CIRCLE G:\Mega Scholarship Test - MEDICAL.doc Dr. Sangeeta Khanna Ph.D a. b. c. d. In test tube X, brown colour intensifies since backward reaction is favoured at low temperature In test tube Y, brown colour intensifies since backward reaction takes place at room temperature In test tube Z, brown colour intensifies since high temperature favours the backward reaction. Brown colour of test tubes X, Y and Z remains same since there is no effect of change in temperature on the reaction C Sol. It is an exothermic reaction, hence the forward reaction is favoured at low temperature which means colourless N2O4 will be formed resulting in decrease in intensity of brown colour. High temperature favours backward reaction resulting in formation of NO2, thus intensifying brown colour. 5. 0.05 mole of NaOH is added to 5 litres of water. What will be the pH of the solution? a. 12 A b. 7 d. 10 0.05 = 0.01 or 10–2 M 5 Sol. Conc of NaOH = 6. c. 2 [OH–] = 10–2 M Kw 10 14 [H ] 10 12 2 [OH ] 10 pH = - log [H+] = - log 10–12 = 12 In Lassaigne’s test, which of the following organic compounds would produce a blood-red colour when its sodium extract is treated with FeCl3 solution? a. CH 3 C H SO 3H b. H2SO4 | Cl CH3 | c. H2N d. CH2 C H SO 3H CO2H | NH 2 7. D Which of the following compounds has wrong IUPAC name? a. CH3 – CH2 – CH2 – COO – CH2CH3 Ethyl butanoate b. CH 3 C H CH 2 CHO 3-Methyl-butanal | CH 3 c. CH 3 CH C H CH 3 2-Methyl-3-butanol | | OH CH3 O || d. CH 3 C H C CH 2 CH 3 2-Methyl-3-pentanone | CH3 C Sol. The correct name is 3-methyl-2-butanol 8. A mixture of C2H6, C2H4 and C2H2 is bubbled through alkaline solution of copper (I) chloride, contained in Woulf’s bottle. The gas coming out is 9. a. original mixture b. C2H6 c. C2H6 and C2H4 mixture d. C2H4 and C2H2 C Which of the following property of hydrogen does not resemble to alkali metals? a. Unipositive ion c. Ionization energy C Dr. Sangeeta Khanna Ph.D b. Formation of oxides d. Formation of sulphides 3 CHEMISTRY COACHING CIRCLE G:\Mega Scholarship Test - MEDICAL.doc Dr. Sangeeta Khanna Ph.D 10. If the solubility of salt A2B3 is x mol L – 1, then its solubility product is equal to: a. 12 x3 b. 108x3 c. 36 x5 d. 108x5 D Sol. A2B3 2A+3 + 3B–2 x 2x 3x Ksp = (2x)2 (3x)3 = 108 x5 11. The ratio of area of orbit of first excited state of electron to the area of orbit of ground level, for hydrogen atom, will be: a. 16 : 1 b. 4 : 1 A Sol. For first excited state, n = 2 A 2 r22 n 24 16 A 1 r12 n14 1 c. 8 : 1 d. 2 : 1 n2 0.529 Å r Z 12. Diborane has a. 2 two - centre – two – electron bonds and 4 three – centre – three – electron bonds. b. 4 two – centre – two – electron bonds and 2 three – centre – two – electron bonds c. 3 two – centre – two – electron bonds and 3 three – centre – three – electron bonds d. all six identical bonds. B Hb Ht Sol. Ht Ht B or B Ht B Ht Ht Hb 97° 1.33Å 1.19Å Hb Ht B 121.5° Ht Hb 1.77Å Thus the diborane molecule has four two-centre-two-electron bonds (2c – 2e bonds) also called usual bonds and two three-centre-two-electron bonds (3c – 2e) also called banana bonds. Hydrogen attached to usual and banana bonds are called Ht (terminal H) and Hb (bridged H) respectively. 13. Which of the following is correct order of stability of alkene? a. CH3 – CH = CH2 < < b. CH3 – CH = CH2 < c. < < < < < CH – CH = CH 3 2 < < CH3 – CH = CH2 < < d. B Sol. As the number of - H increases stability of alkene increases. 14. Temperature at which the CO2 has the same RMS velocity as that of H2 at STP? a. 6600 K C T T Sol. 1 2 M1 M2 b. 6060 K c. 6006 K d. 6.006 K 273 T2 2 44 273 × 22 = T2 ; Dr. Sangeeta Khanna Ph.D T2 = 6006 K 4 CHEMISTRY COACHING CIRCLE G:\Mega Scholarship Test - MEDICAL.doc Dr. Sangeeta Khanna Ph.D 15. A liquid (v.p. = 100 m Hg) is transferred from a vessel of 10 ml capacity to 1000 ml capacity, hence its vapour pressure 1 th times 10 d. Remain as such a. increases 10 times b. Decreases c. Increases 100 times D 16. Which of the following substituted benzene derivatives would produce three isomeric products when one more substituent is introduced? Cl Cl Cl Cl Cl Cl Cl I II III IV a. I, II and III b. I c. II and IV D 17. The most stable conformation of 2, 3-dimethylbutane is CH3 CH3 CH3 H CH3 H CH3 H CH3 a. d. I and III b. H H3C CH3 H CH3 H3C c. H CH3 CH3 d. CH3 H3C H H B 18. In which the following molecules -electron density in ring is maximum? NO2 a. O NH2 b. CH3 CH3 OCH3 c. d. B Θ Sol. O is better donor than – NH2 and – OCH3 CH3 | H SO 4 19. CH 3 C CH 2 OH 2 | P ; P is (Major ) CH3 CH3 CH3 a. CH 3 C CH CH 3 CH3 b. CH 2 C CH 2 CH 3 | | | c. CH 3 C CH 2 A 20. What is the order of stability of N2 and its ions? d. none b. N2 N2 N2 N22 d. N22 N2 N2 N2 a. N2 N2 N2 N22 c. N2 N2 N2 N22 A Sol. Bond order of N2 = 3, N2 = 2.5, N2 = 2.5 and N22 is 2. Higher the bond order, more is the stability. Dr. Sangeeta Khanna Ph.D 5 CHEMISTRY COACHING CIRCLE G:\Mega Scholarship Test - MEDICAL.doc Dr. Sangeeta Khanna Ph.D 21. In which of the following, the order is not in accordance with the property mentioned. a. Li < Na < K < Rb – Atomic radius b. F > N > O > C – Ionisation enthalpy c. Si < P < S < Cl – Electronegativity d. I < Br < F < Cl – Electronegativity D Sol. Electronegativity decreases down the group. 22. If the velocity of an electron in Bohr’s first orbit is 2.19 × 106 m s-1, what will be the de Broglie wavelength associated with it? a. 2.19 × 10-6 m C b. 4.38 × 10-6 m c. 3.32 × 10-10 m d. 3.32 × 1010 m h 6.626 10 34 J s m 9.11 10 31kg 2.19 10 6 m s -1 = 3.32 × 10-10 m 23. 1.525 g of an organic compound was Kjeldahlised and the ammonia so produced was passed into N 30 ml of 1 N HCl solution. The remaining HCl was further neutralized by 120 ml of NaOH solution. 10 The percentage of nitrogen in the compound is: Sol. a. 16.52% A b. 5.50 % c. 0.5% d. 20.4% 1 30 1 120 10 14 10 Sol. Percentage N = 1000 1.525 = 16.52% 24. What volume of 5 M Na2SO4 must be added to 25 mL of 1 M BaCl2 to produce 10 g BaSO4? [M.Wt. of BaSO4 = 233] a. 8.58 mL b. 7.2 mL c. 10 mL d. 12 mL A Sol. Na2SO4 + BaCl2 BaSO4 + 2NaCl m 10 No. of moles of BaSO4 = 0.0429 M 233 No. of moles of Na2SO4 needed = 0.0429 MV 5 V 0.0429 or 0.0429 1000 1000 V = 8.58 mL 25. In a reaction container, 100 g hydrogen and 100 g Cl2 are mixed for the formation of HCl gas. What is the limiting reagent and how much HCl is formed in the reaction? a. H2 is limiting reagent and 36.5 g of HCl are formed. b. Cl2 is limiting reagent and 102.8 g of HCl are formed. c. H2 is limiting reagent and 142 g of HCl are formed. d. Cl2 is limiting reagent and 73 g of HCl are formed. B Sol. H2 Cl 2 2HCl 2g 71 g 73 g 2g H2 reacts with 71 g Cl2 71 100 g H2 will react with ×100 = 3550 g Cl2 2 Hence, Cl2 is the limiting reagent 71 g Cl2 produces 73 g HCl 73 100 102.8 g HCl 100 g Cl2 will produce 71 Dr. Sangeeta Khanna Ph.D 6 CHEMISTRY COACHING CIRCLE G:\Mega Scholarship Test - MEDICAL.doc Dr. Sangeeta Khanna Ph.D 26. Strength of 10 volume hydrogen peroxide solution means a. 30.35 g L-1 A Sol. 2H2O2 2H2O 68 g b. 17 g L-1 c. 34 g L-1 d. 68 g L-1 O2 22.4 L at STP 22.4 L O2 is given by 68 g of H2O2 68 10 L O2 is given by 10 30.35 g L-1 22.4 X 27. Residue + Colourless gas heating water excess of Z CO2 Y Identify X, Y and Z X a. Ca(HCO3)2 c. CaCO3 B Sol. CaCO3 (X) Y CaCO3 CaO heat (Z) X b. CaCO3 d. CaCO3 Y Ca(OH)2 CaO Z Ca(HCO3)2 Ca(HCO3)2 CaO + CO2 H2O heating Ca(HCO3)2 Z Ca(OH)2 Ca(OH)2 excess of CO2 Ca(OH)2 (Y) 28. What are the oxidation states of phosphorus in the following compounds? H3PO2, H3PO4, Mg2P2O7, PH3, HPO3 a. +1, +3, +3, +3, + 5 b. +3, +3, +5, +5, +5 c. +1, +2, +3, +5, +5 d. +1, +5, +5, -3, +5 D Sol. H3PO2 : +3 + x – 4 = 0 x = +1 H3PO4 : + 3 + x – 8 = 0 x = +5 Mg2P2O7 : +4 + 2x – 14 = 0 x = +5 PH3 : x + 3 = 0 x = - 3 HPO3 : + 1 + X – 6 = 0 x = +5 29. A solution containing Mn2+, Fe2+, Zn2+ and Hg2+ with a molar concentration of 10–3 M each is treated with 10-16 M sulphide ion solution. Which ions will precipitate first if Ksp of MnS, FeS, ZnS and HgS are 10-19, 10-23, 10-20 and 10-54 respectively? a. FeS b. MnS c. HgS C Sol. M2+ + S2– MS Lower the value Ksp, lower will be solubility. Hence HgS will precipitate first. Dr. Sangeeta Khanna Ph.D 7 d. ZnS CHEMISTRY COACHING CIRCLE G:\Mega Scholarship Test - MEDICAL.doc Dr. Sangeeta Khanna Ph.D 30. What will be the solubility of AgCl in 0.05 M NaCl aqueous solution if solubility product of AgCl is 1.5 × 10-10? a. 3 × 10–9 mol L–1 A Sol. Ksp = [Ag+] [Cl– ] [Cl–] = NaCl = 0.05 M b. 0.05 mol L–1 c. 1.5 × 10–5 mol L–1 d. 3 × 109 mol L–1 1.5 10 10 3 10 9 M 0.05 [Ag+] = solubility = 3 × 10–9 M 31. Solution of a monobasic acid has a pH = 5. If one mL of it is diluted to 1 litre, what will be the pH of the resulting solution? Ag a. 3.45 B Sol. pH = 5, [H+] = 10–5 M b. 6.96 c. 8.58 d. 10.25 10 5 10 8 M 1000 Total [H+] = 10-8 + 10–7 = 1.1 × 10–7 pH = -log [H+] = -log (1.1 × 10-7) = 6.96 32. Graphs between pressure and volume are plotted at different temperatures. Which of the following isotherms represents Boyle’s law as PV = constant? After dilution = T1 T2 T3 P P T3 T2 T1 PV T1 T2 T3 1/V P V (i) log P logV (iii) (ii) (iv) a. Only (ii) is correct representation of Boyle’s law. b. Only (iv) is correct representation of Boyle’s law. c. All are correct representations of Boyle’s law. d. None of these representation is correct for Boyle’s law C 33. Given below is the table showing shapes of some molecules having lone pairs of electrons. Fill up the blanks left in it Molecule type AB2E2 bp 2 lp P Shape Example Bent H2O AB3E2 3 2 Q ClF3 AB5E 5 R S BrF5 AB4E2 4 2 T U a. b. c. d. C P 2 4 2 3 Q Square pyramidal T-shaped T-shaped Square planar Dr. Sangeeta Khanna Ph.D R 2 5 1 2 S T-shaped Square planar Square pyramidal T-shaped 8 T Square planar Square pyramidal Square planar Square pyramidal U H2O2 SO3 XeF4 BrCl3 CHEMISTRY COACHING CIRCLE G:\Mega Scholarship Test - MEDICAL.doc Dr. Sangeeta Khanna Ph.D 34. Match the molecules given in column I with their shapes given in column II and mark the appropriate choice. Column I (Molecule) Column II (Shape) (A) SF6 (i) (B) SiCl4 (ii) (C) AsF5 (iii) (D) BCl3 (iv) a. (A) (iv), (B) (ii), (C) (iii), (D) (i) b. (A) (iv), (B) (i); (C) (ii), (D) (iii) c. (A) (iii), (B) (i), (C) (ii), (D) (iv) d. (A) (ii), (B) (iii), (C) (i), (D) (iv) B Sol. (A) SF6 Octahedral (B) SiCl4 Tetrahedral (C) AsF5 Trigonal bipyramidal (D) BCl3 Trigonal planar 35. In the given graph, a periodic property (R) is plotted against atomic numbers (Z) of the elements. Which property is shown in the graph and how is it correlated with reactivity of the elements? a(520) (R) b(496) c(419) d(403) e(374) (Z) a. Ionisation enthalpy in a group, reactivity decreases from a e. b. Ionisation enthalpy in a group, reactivity increases from a e c. Atomic radius in a group, reactivity decreases from a e. d. Metallic character in a group, reactivity increases from a e. B Sol. I.E. in a group decreases and reactivity increases. 36. Match the column I with column II and mark the appropriate choice. Column – I Column – II (Atom) (No. of unpaired electrons) (A) 15P (i) 6 unpaired electrons (B) 24Cr (ii) 2 unpaired electrons (C) 26Fe (iii) 3 unpaired electrons (D) 14Si (iv) 4 unpaired electrons a. (A) (ii), (B) (i), (C) (iii), (D) (iv) b. (A) (i), (B) (iii), (C) (ii), (D) (iv) c. (A) (iii), (B) (i), (C) (iv), (D) (ii) d. (A) (iv), (B) (ii), (C) (i), (D) (iii) C Dr. Sangeeta Khanna Ph.D 9 CHEMISTRY COACHING CIRCLE G:\Mega Scholarship Test - MEDICAL.doc Dr. Sangeeta Khanna Ph.D Sol. 15P = [Ne] 3s2 3p3 24Cr = [Ar] 4s1 3d5 26Fe = [Ar] 4s2 3d6 14Si = [Ne] 3s2 3p2 37. Match the mass of elements given in column I with the no. of moles given in column II and mark the appropriate choice. Column – I (A) 28 g of He (B) 46 g of Na (C) 60 g of Ca (D) 27 g of Al Column – II (i) 2 moles (ii) 7 moles (iii) 1 mole (iv) 1.5 moles a. (A) (iv), (B) (iii), (C) (ii), (D) (i) b. (A) (i), (B) (iii), (C) (ii), (D) (iv) c. (A) (iii), (B) (ii), (C) (i), (D) (iv) d. (A) (ii), (B) (i), (C) (iv), (D) (iii) D 28 46 Sol. (A) : 28 g of He = = 7 mol (B) : 46 g of Na = 2 mol 4 23 60 27 (C) : 60 g of Ca = (D) : 27 g of Al = = 1 mol 1.5 mol 40 27 38. What is the relationship between the two structures shown? CH3 Cl CH3 Cl a. Constitutional isomers b. Stereoisomers c. Different drawing of the same conformation of the same compound d. Different conformation of the same compound A Sol. Position isomers CH3 C = CH2 39. + HBr A (Major) Product (A) of the above reaction is: Br Br a. Br b. Br c. d. A CH3 Sol. C – CH3 ring expansion Dr. Sangeeta Khanna Ph.D CH3 CH3 shift 10 Br CH3 – CH3 Br – CHEMISTRY COACHING CIRCLE G:\Mega Scholarship Test - MEDICAL.doc Dr. Sangeeta Khanna Ph.D 40. Among the following in which pair, the second ion is more stable than first? a. b. and c. CH2 and d. and and D Section – B (Assertion & Reason) a. b. c. d. 1. Both assertion and reason are true and reason is the correct explanation of assertion. Both assertion and reason are true but reason is not the correct explanation of assertion. Assertion is true but reason is false. Both assertion and reason are false. Assertion: On moving down the group, ionisation enthalpy decreases. Reason: With increase in size of the atom the force of attraction between the nucleus and valence electrons decreases a. (A) b. (B) c. (C) d. (D) A Sol. I.E. decreases down the group due to increase in atomic size and the outermost electron being increasingly farther from the nucleus, there is an increased shielding of the nuclear charge by the electrons of the inner levels. 2. Assertion: The energy of the electron in a hydrogen atom has a negative sign for all possible orbits. Reason: When the electron is attracted by the nucleus and is present in orbit n, the energy is emitted and its energy is lowered. 3. a. (A) b. (B) c. (C) d. (D) A Assertion: Hydrogen peroxide acts as an oxidizing agent as well as a reducing agent Reason: It contain both hydrogen and oxygen 4. a. (A) b. (B) c. (C) d. (D) B Assertion: The carbonate of lithium decomposes easily on heating to form lithium oxide and CO2 Reason: Lithium being very small in size polarises large carbonate ion leading to the formation of more stable Li2O and CO2 5. a. (A) b. (B) c. (C) d. (D) A Assertion: A solution of NH4Cl in water is acidic in nature Reason: Ammonium ions formed undergo hydrolysis to form NH4OH which is a weak base and remains unionized in solution a. (A) b. (B) A Sol. NH4Cl NH 4 Cl NH4Cl + H2O NH 4 OH HCl weak base 6. c. (C) d. (D) strong acid HCl H+ + Cl– (Acidic) Assertion: Soft water lathers with soap but not hard water. Reason: Hard water contains calcium and magnesium salts which react with soap to form insoluble salts which form scum and not lather a. (A) b. (B) Dr. Sangeeta Khanna Ph.D c. (C) 11 d. (D) CHEMISTRY COACHING CIRCLE G:\Mega Scholarship Test - MEDICAL.doc Dr. Sangeeta Khanna Ph.D A Sol. 2RCOONa + Ca2+ (RCOO)2Ca + 2Na+ 2RCOONa Mg2+ (RCOO)2Mg + 2Na+ 7. Assertion: 1 mole of water is equal to 6.023 × 1023 molecules. Reason: The mass of one mole of a substance in grams is called the molar mass a. (A) b. (B) c. (C) d. (D) B Sol. Both statements are true but independent of each other. 8. Assertion: The gases show ideal behaviour when the volume occupied is large so that the volume of the molecules can be neglected in comparison to it. Reason: The behaviour of the gas becomes more ideal when pressure is very low 9. a. (A) b. (B) c. (C) d. (D) B Assertion: Heat of neutralization of HNO3 and NaOH is same as that of HCl and KOH. Reason: Both HNO3 and HCl are strong acids and NaOH and KOH are strong bases. a. (A) b. (B) c. (C) d. (D) A Sol. Heat of a strong acid and strong base is always same since neutralization involves reaction between H+ and OH– ions. 10. Assertion: At high altitudes, liquids boil at lower temperatures in comparison to that of sea level. Reason: At high altitudes, atmospheric pressure is high a. (A) b. (B) c. (C) C Sol. Due to low atmospheric pressure, the liquid boils at lower temperature. d. (D) Section – C (Assertion & Reason) a. b. c. d. 1. Both assertion and reason are true and reason is the correct explanation of assertion. Both assertion and reason are true but reason is not the correct explanation of assertion. Assertion is true but reason is false. Both assertion and reason are false. Assertion: Viscosity of liquids decreases as the temperature rises. Reason: At high temperature, molecules have high kinetic energy and can overcome the inter molecular forces to flow faster. a. (A) b. (B) c. (C) d. (D) A,B Sol. Viscosity of liquids decreases as the temperature rises. 2. Assertion: An exothermic process which is non–spontaneous at high temperature may become spontaneous at low temperature. Reason: Spontaneity is also favoured by increase in entropy. 3. a. (A) b. (B) c. (C) d. (D) A Assertion: Kp can be less than, greater than or equal to Kc. Reason: Relation between Kp and Kc depends on the change in number of moles of gaseous reactants and products (n). a. (A) A Sol. Kp = Kc (RT)n b. (B) Dr. Sangeeta Khanna Ph.D c. (C) 12 d. (D) CHEMISTRY COACHING CIRCLE G:\Mega Scholarship Test - MEDICAL.doc Dr. Sangeeta Khanna Ph.D 4. Assertion: HNO3 acts only as oxidizing agent while HNO2 can act both as a reducing agent and an oxidizing agent. Reason: In HNO3, oxidation state of nitrogen is +5 which is maximum. In HNO 2, oxidation state of nitrogen is +3 which can change from –3 to +5. a. (A) b. (B) c. (C) d. (D) A Sol. Since in HNO2 oxidation state of nitrogen can increases or decrease it can act as an oxidizing as well as a reducing agent. 5. Assertion: Carbon monoxide is a poisonous gas. Reason: Carbon monoxide combines with haemoglobin to form carboxyhaemoglobin with stops absorption of oxygen. 6. a. (A) b. (B) c. (C) d. (D) A Assertion: Carbon atom is tetravalent though it has two unpaired electrons. Reason: Carbon has unique ability to form p - p multiple bonds like C = C, C C. a. (A) b. (B) c. (C) d. (D) B Sol. Carbon is tetravalent due to empty p-orbitals which hybridise in excited state to give sp3 hybridisation with one electron each in 2s and 3p-orbitals showing tetravalency. C (ground state) 1s 2s 1s 2s 2p C (ground state) 2p Hybrid orbitals 7. Assertion: CO2 is a gas at room temperature while SiO2 is crystalline solid. Reason: SiO2 is a network of silicon and oxygen atoms joined by multiple bonds. a. (A) b. (B) c. (C) d. (D) C Sol. SiO2 is a network of Si and O atoms joined by single bonds in a tetrahedral manner. 8. Assertion: The reaction, C2H5Br + 2Na + C2H5Br C2H5C2H5 + 2NaBr is known as Wurtz reaction. Reason: The reaction is carried out in presence of dry ether. 9. a. (A) b. (B) c. (C) d. (D) B Assertion: cis-Form of alkene is found to be more polar than the trans-form. Reason: Since the groups are in opposite directions, the dipole moments of bonds cancel each other making trans form almost non-polar a. (A) A b. (B) CH3 CH3 H d. (D) CH3 H C=C Sol. c. (C) C=C H CH3 cis-But-2-ene ( = 0.33 D) H Trans-But-2-ene ( = 0) 10. Assertion : Tropylium ion has delocalised -electron cloud. Reason: It has 12 electron in conjugation therefore it is antiaromatic. a. (A) C b. (B) Dr. Sangeeta Khanna Ph.D c. (C) 13 d. (D) CHEMISTRY COACHING CIRCLE G:\Mega Scholarship Test - MEDICAL.doc
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