Physical Chemistry Questions

Rate of the reaction in terms of the pressure of the reactant assume rate as an extensive property is CH CHO CO CH 1 3 VdPCH CHO RT dt dPCH CHO 1 RTV dt 2 4 1 dpCH CHO RT dt nCH CHo dpCH CHO V dt

You take 224 5 g of a solid at 30 0 C and let it melt in 425 g of water The water temperature decreases from 85 1 C to 30 0 C Calculate the heat of fusion of this solid O 436 J g O218 J g O 650 J g O cannot solve without the heat capacity of the solid

24 For the following reaction pick out the incorrect interpretations 2A g Big4C Da 1 2 moles of A 1 mole of B reacts to form 4 moles of C 1 mole of D 2 2 gm of A 1 gm of B reacts to give 4 gm of C 1 gm of D 3 2 molecules of A 1 molecule of B reacts to give 4 molecules of C 1 molecule of D 4 2 vol of A 1 vol of B reacts to give 4 vol

5 If first ionization ptoential of an atom is 36 V then the second excitation potential will be 1 10 2 V 2 12 V 3 27 V 4 32 V

Pre Medical Chemistry 65 0 The rate constant the activation energy and the Frequency factor of a chemical reaction at 25 C are 3 x 10 s 104 4 kJ mol and 6 0 x 10 4 respectively the value of the rate constant as Tis 1 2 x 10 S 3 Infinity 2 6 x 10 4 4 3 6 x 100 CK0099

141 From the reactions C s 2H g CH g AH X Kcal C g 4H g CH g AH X Kcal CH g CH g H g AH Y Kcal Bond energy of C H bond is 1 kCal mol 3 kCal mol 4 2 Y kCal mol 4 X kCal mol

a RT b C FRI 12 A plot of Gibbs energy of a reaction mixture against the extent of the reaction is a minimum at equilibrium c maximum at equilibrium 200 TO zero at equilibrium d None of these

34 R 3 bromocyclopentene shown below reacts with 34 R 3 bromocyclopentene Br CCI a Turu EER 3rom Br CCl4 to form two products Y and Z Y is not optically active does not rotate plane polarized light What is the structure of Y 1 3 BE Br P B BT Br Br Br Br CCl4Y Z 2 4 Br Br Br Br 1 3 B Br Br Br 3 Br CC1Y Z 2 4 8 4977 9 Br BE Br 2 3 4 Ic

This section contains 20 SINGLE CORRECT Fe CN 6 Chem Section A Which of the following complex ions obeys Sidgwick s effective atomic number EAN rule Co CO 3NO Cr NH3 2 en 2 Read More

216 81m 150 90nz 6 595n328 412 kJ s lving Equations 1 through 3 simultaneously yields n 92 0 mol C H5OH s

3 Thermal decomposition of HCOOH is a first order reaction and the rate constant at T K is 4 606 x 10 s The time required to decompose 90 of initial quantity of HCOOH at T K in second is A 100 B 500 C 1000 D 50

ALLEN 128 The temperature of a 5 ml of strong acid increases by 5 C when 5 ml of a strong base is added to it If 10 ml of each are mixed temperature should increase by O 134

254 Pre Medical Chemistry 140 Bond dissociation enthalphies of H g and N g are 436 0 kJ mol and 941 8 kJ mol respectively and 14 enthalpy of formation of NH g is 46 kJ mol What is enthalpy of atomization of NH g 1 390 3 kJ mol 2 1170 9 kJ mol

51 On intreasing the temperature the rate of a reaction Malways increases b always decreases c first increases and then decreases d may increase or decrease depending upon the nature of the reactic

7 Equal volumes of three acid solutions of pH 3 489 and 5 are mixed in a vessel What will be the H ion concentration in the mixture 1 3 7 x 10 4 M 3 1 11 x 10 3 M 2 3 7 x 10 3 M 4 1 11 x 10 4 M 15

Use the following table to find the standard reduction potential E Red for the half reactions listed below Given Zn 2e Zn E Red 0 76V E cell E Catho Measured voltages for galvanic cells using standard conditions Anode E V Zn Zn Cathode Cu Cu Cu Cu Bry Br Zn Zn Cl CI Ag Ag a Cl 2e 2 CI b Ag e Ag E Red E Red SHE Zn Zn K K Ag Ag K K 1 10 0 34 1 85 2 16 0 56 3 72

What will be the effect of adding 100 ml of 0 001 M HCl solution to 100 ml of a solution having 0 1 M HA The acid dissociation constant of HA is 10 5 a The degree of dissociation of HA will decrease but the pH of solution remains unchanged b The degree of dissociation of HA remains unchanged but the pH of solution decreases c Neither degree of dissociation nor pH of solution will change d The degree of dissociation as well as

1 0 200 1 575 gram of oxalic acid COOH 2 XH O are dissolved in water and the volume made upto 25C ml On titration 8 34 ml of this solution requires 12 5 ml of N 15 NaOH solution for complete neutralization Calculate x The fitting reaction involves x number of aryl halide molecules x is

76 A Product follows the first order kinetics If the half life period of the reaction at Alinal 0 2 mol L is 20 min then the value of rate constant would be 1 4 s 3 4 lit mol min 2 201 4 0 034 min CK0083

19 For the reaction N2 g O g 2NO g the equilibrium constant is K The equilibrium constant is K for the reaction 2NO g O g 2NO2 g What is K for the reaction NO2 g 1 2N g O g AIPMT 2011 a c 1 KjK2 1 4 KjK Ciron 1 b d 105 2K K2 1 KjK2 1 2

OIS 182 166 H g O g H O AH2 68 32kCal Heat of vapourisation of water at 1 atm and 25 C is 10 52 kCal The standard heat of formation in kcal of 1 mole of water vapour at 25 C is 1 10 52 2 78 84 3 57 80 4 57 80

1 and Br are added to a solution containing 1M each off and Br ions Which of the following action will take place Given Standard reduction potentials of Land Br are 0 53 and 1 09 Volts repectively 1 lodine will reduce bromide ions 2 Bromine will reduce lodide ions 3 lodide ions will reduce bromine 4 Bromide ion will reduce lodine

1 108 kcal 3 98 kcal 2 196 kcal 4 54 kCal TC017 59 i S s 3 2 O g SO g 2x kl ii SO g 2O g SO g y kCal Calculate the heat of formation of SO 1 2x y 2 2x y 3 x y 4 2x y

32 The heat of combustion of C H C H and H are 1409 5 kJ 1558 3 kJ and 285 6 kJ The heat of hydrogenation of ethene is 1 136 8 kJ 3 273 6 kJ 2 13 68 kJ 4 1 368 kJ

A SALT SOLUTION IS OBTAINED BY DISSOLVING 40g OF SA LT IN 60g OF WATER WHAT MUST BE DONE TO MAKE THIS SALT SOLUTION 50 OPTIONS 1 ADD 20g OF WATER TO THE SOLUTION 2 ADD 20g OF SALT TO THE SOLUTION 3 ADD 10g OF SALT AND 10g OF WATER TO THE SOLUTION 4 BOTH 1 AND 2 PLEASE EXPLAIN CLEARLY AND STEP BY STEP WI TH FULL EXPLANATION

The following galvanic cell has a potential of 1 21 V at 25 C Hg 1 Hg Br s Br 0 1 M MnO4 0 1 M Mn 0 1 M H 0 1 M Pt Calculate the solubility product Hg Br at 25 C Given E 2 Hg Hg 1 0 80 V E MnO4 H Mn 1 51 V

31 The change in the enthalpy of NaOH HCI NaCl H O is called 1 Heat of neutralisation 2 Heat of reaction 3 Heat of hydration 4 Heat of solution 137 E 2 1 3 ion 20

ALLEN 150 The heat of combustion of yellow phosphorous and 156 If H red phosphorous are 9 91 kJ and 8 78 kJ respectively The heat of transition of yellow phosphorous to red phosphorous is 1 18 69 kJ 2 1 13 kJ K AH KOH

165 The enthalpy of vapourisation of liquid water using the data H 0 H O 0 AH 285 77 kJ mol H 0 H O AH 241 84 kJ mol 2020 3 3 93 kJ mol 527 61 kJ mol 2 43 93 kJ mol 4 527 61 kJ mol

0131 124 Heat of formation of CO is 94 0 kCal What would be the quantity of heat liberated when 3 g of graphite is burnt in excess of oxygen 2 2 35 kcal 4 31 20 1 23 5 kCal 3 90 Sl

ALLEN SOME OTHER HEAT OF REACTIONS 45 The enthalpy change for the reaction 2C graphite 3H2 g CH g is called 1 Enthalpy of formation 2 Enthalpy of combustion

on HEAT OF NEUTRALIZATION 125 The amount of heat liberated when one mole of NH OH reacts with one mole of HCl is 1 13 7 kCal 2 More than 13 7 kCal 4 Cannot be predicted 3 Less than 13 7 kCal 2 EXEP65

TC0153 37 Energy required to dissociate 4g of gaseous hydrogen into free gaseous atoms is 208 kCal at 25 C The bond energy of H H bond will be 1 1 04 kcal 2 10 4 kCal 3 104 kCal 4 1040 kCal 2020 2

TC0152 6 The bond energies of F Cl Br and I are 155 4 243 6 193 2 and 151 2 kJ mol respectively The strongest bond is 1 F F 3 Br Br 2 2 CI CI 4 I I TC0153

2 are heat TC0154 138 Heat evolved in the reaction H Cl 2HCl is 182 kJ Bond energies of H H and Cl Cl are 430 and 242 kJ mol respectively The H Cl bond energy is 1 245 kJ mol 3 336 kl mott 2 427 kJ mol 4 154 kl mort

The vapour pressures of pure liquids A and B are 300 and 800 torr respectively at 25 C When these two liqu are mixed at this temperature to form a solution in which mole fraction of B is 0 92 then the total vapour pressure is observed to be 0 95 atm Which of the following is true for this solution O AVmix 0 OAH mix 0 O AVmix 0

When 0 1 m CH3COOH is present in a solvent it shows elevation in boiling point of 0 75 C Acid dissociation constant will be K 5 K Kg mol 1M 1m 1 5 x 10 2 5 X 10 3 3 10 2 4 10

Q27 NTA Test 32 Single Choice The solubility product of AgCl is 1 8 x 101 Precipitation of AgCl will occur only when equal volumes of which of the following solution are mixed A 10 M Ag and 10 M CI C 10 M Ag and 10 M Crathongo B 10 M Ag and 10 D 10 10 M Ag and 10 MCT mothong mathon M CT othongo

The wavelengths of light absorbed by the complexes Ni H O 2 Ni en Ni H O en are A A2 A respectively The correct order of wavelengths is A A A Ag B A3 A A C A A3 D A A3 A

74 A reaction is of first order After 100 minutes 75 gm of the reactant A are decomposed when 100 gm are taken initially calculate the time required when 150 gm of the reactant A are decomposed the initial weight taken is 200 gm 1 100 minutes 3 150 minutes 2 200 minutes 4 175 minutes CK0081 81 A O O 1 2 3

118 The following are the heats of reactions i AH of H O 68 3 kCal mol 1 AHomb of C H 337 2 kCal mol ii AHomb of C H 363 7 kCal mol Then heat change C H H CH is 1 716 1 kCal 3 41 8 kCal ession for the reaction 2 337 2 kCal 4 579 5 kCal

9 The enthalpy change for the reaction H g CH g CH g is The bond energies are in kCal mol H H 103 C H 99 C C 80 C C 145 1 10 kCal mol TC0155 2 10 kCal mol 3 30 kCal mol 4 30 C

of 97 97 For a reaction in which case the activation energies of forward and reverse reactions are equal 1 AH 0 2 AS 0 3 The order is zero 4 There is no catalyst CK0107

151 2CO Oa 2CO X kJ 2gl In the above equation X kJ refers to 1 Heat of formation of CO 2 Heat of vapourisation 3 Heat of reaction 4 Heat of sublimation

Cl by NaOH is 135 Among the following for which reaction heat of alization of HCN reaction represents bond energy of HCI 1 HCl g H g Cl g The energy of 2 HCl g 2H g 2Cl g 3 2HCl g H g Cl g 4 HCl g H g Cl g 8 kJ 8 kJ TC0145

Bond energy of C H bond is Given that the heat of formation of CH4 heat of sublimation of carbon and heat of dissociation of H are 74 8 719 6 and 435 4 KJ mol respectively 1 1665 2 KJ 3 816 3 KJ 2 416 3 KJ 4 614 2 KJ

4 Can t be predicted CK0093 86 The rate of a chemical reaction doubles for every 10 C rise in temperature If the temp is increased by 60 C the rate of reaction increases by 1 20 times 2 32 times 3 64 times 4 128 times 94

3 1 25 x 10 min CK0067 A graph between t and concentration for nth orde reaction is a straight line Reaction of this nature is completed 50 in 10 minutes when concentration is 2 mol L This is decomposed 50 in t minutes at 4 mol L n and t are respectively t 4 4 x 105 min 1 0 20 min 3 1 20 min conc 2 1 10 min 4 0 5 min CK0068

2 2H 2 19 e vakyl 4 drogen ion concentration of a 10 8 M HCI aqueous solution at 298 K Kw 10 14 is 1 1 0 x 10 6 M 2 1 0525 x 10 7 M 3 9 525 x 10 8 M 4 1 0 x 10 8 M AIIMS 2006 40 mL of 0 1 M ammoni 20 mL of Q 1 M HCI KC1 NaCl

Shombic O SO AH 297 5 kJ Sumonoclinic O g SO AH 300 kJ The data can predict that 1 Rhombic sulphur is yellow in colour 2 Monoclinic sulphur has metallic lusture 3 Monoclinic sulphur is more stable