Physical Chemistry Questions

1 litre of a hydrocarbon weighs as much as one litre of CO The molecular formula of hydrocarbon is 1 C H 8 3 C H 4 Fou 2 C H 4 C H

For a first order Pseudo reaction CH COOC H H O CH COOH C H OH The net rate is given by dx Rate 4 x 104 CH3COOC2H5 2 x 104 CH3COOH C H5OH dt If the equilibrium constant of the reaction will be 2 x 10 x then the value of x

Decreasing order first having highest and then others following it of mass of pure NaOH in each of the aqueous solution i 50 g of 40 w W NaOH ii 50 mL of 50 w V NaOH d 1 2 g mL 1 g mL iii 50 g of 15 M NaOH d soln 1 i ii iii 2 iii ii i 3 ii iii i 4 ii i iii

For homogeneous gaseous reaction A B C D the initial pressure was Po while pressure after time t was P if P P The expression for the rate constant K is 1 K 2 K 3 K 2 303 log 2 p 2P 0 3P P t 2 303 t 2 303 t log log 3Po 0 2P P 0 Po Po P 2P

If you dissolved the salt methylammmonium cyanide CH3NH3 CN in water what type of solution would you expect to have K HCN 4 9 x 10 10 Kb CH3NH 4 4 x 10 4 Neutral Can not be determined from the information given Basic Acidic

Which of the following metal does not react with the solution of copper sulphate Zn Fe Ag Mg

Two moles of triatomic linear gas are taken through a reversible process starting from A as shown in figure The volume ratio V NAX 4 If the temperature at A is 73 C then total enthalpy change in both steps is X R joules X Report the value of Vol L 100 C B A Temperature K Correct answer 42 00

A compound X undergoes through first order Y decomposition in Y and Z as follows X The rate of reaction of X can be expressed as 1 K K X 3 K Z a Tower K 2 N 2 K Y 4 K K Y Z

Which of the following statements about Avogadro s law is correct A At constant temperature and pressure equal volumes of all gases contain same number of molecules B The number of molecules in one litre of hydrogen is less than the number of molecules in one litre oxygen at constant temperature and pressure D It did not differentiate between atoms and molecules At constant temperature and pressure different volumes of all gases contain same number of molecules

Chemists commonly use a rule of thumb that an increase of 10 K in temperature doubles the rate of a reaction What must the activation energy be for this statement to be true for a temperature increase from 66 to 76 C Activation energy kJ mol

Which of the following is incorrect about Freundlich adsorption isotherm O It fails at high pressure of the gas It is applicable at low and moderate pressure of the gas O It is applicable at constant temperature O It is applicable at all pressure

Which of the following statement about the composition of the vapour over an ideal 1 1 molar mixture of benzene and toluene is correct Assume that the temperature is constant at 25 C Given Vapour pressure data at 25 C benzene 12 8 kPa toluene 3 85 kPa 2016 a The vapour will contain a higher percentage of benzene b The vapour will contain a higher percentage of toluene The vapour will contain equal amounts of benezene and toluene d Not enough information is given to make a dication c

3 Experimental study of photoelectric effect shows that Photocurrent intensity of light I II saturation current o intensity of light III photoemission occurs only at frequency greate than threshold frequency IV photoemission is an instantaneous process The correct statements are a I and II c I III and IV b I II and III d I II III and IV

A sample of certain mass of an ideal nonlinear polyatomic gas is expanded against constant pressure of 1 atm adiabatically from volume 2L pressure 6 atm and temperature 300 K to state where to state where its final volume is 8L Calculate entropy change in J K in the process Neglect vibrational degrees of freedom Take 1L atm 100J R 8 0 J mol K 0 08 Lt atm K mol log 2 0 3 log 3 0 48 log e 2 3 A 3 312 B 3 312 C 2 693 D 2 693

13 The reaction A B follows first order kinetics The time taken for 0 80 mole of A to produce 0 60 mole of B is 1 hour What is the time taker for conversion of 0 90 mole of A to produce 0 675 mole of B 1 1 hour 2 15 minuto 2 30 minute 4 5 minute

56 For a reaction H g 2 g 2HI g AH 37 5 kJ mol and AS 150 JK mol the temperature at which the reaction will be at equilibrium is 1 200 K 3 300 K 2 250 K 4 350 K 6 6

28 The enthalpy of combustion of H cyclohexene C H and cyclohexane C H are 241 3800 and 3920 kJ per mol respectively Heat of hydrogenation of cyclohexene is AIPMT Prelims 2006 1 121 kJ per mol 2 121 kJ per mol 3 242 kJ per mol Sol Answer 1 4 242 kJ per mol

When the gases sulphur dioxide and hydrogen sulphide m ix in the presence of water the product obtained are wate r and sulphur Here hydrogen sulphide is acting as A An oxidizing agent B Reducing agent

The second ionisation potential of Be is 17 98 eV If the electron in Bet is assumed to move in spherical orbit with a central field of effective nuclear charge Zeff consisting of the nucleus and other electrons If the extent of shielding by the K electrons of Li atom is same as calculated above the ionisation potential of Li will be 1 10 2 eV 3 5 746 eV 2 3 476 eV 4 3 2 eV

em No 37 The LS configurations of the ground state of 2Mg Al 17C1 and 18 Ar are 13 respectively 351 1 S 2P1 2 2P 2 and So 3511 2P3 21 2P3 2 and S 2 2P3 2 and So 2P 1 21 50 3 2P1 2 and S 4 So 2P3 2 Note Give the total solution to find the answer

Determine the order of reaction A g 2 B g the vapour density of the system is determined at different stages of reaction occuring at constant temperature The reaction was started with pure A g Time min Vapour density of reaction mixture 0 42 10 35 20 30

In the following question a statement of assertion is followed by a statement of reason Choose the correct answer out of the following choices Assertion The electrons in different subshells have different energies in a multielectron atom Reason The energy of an orbital depends on n value A B Both assertion and reason are correct and the reason is the correct explanation of the assertion Both assertion and the reason are correct but the reason is not the correct explanation of the assertion C Assertion is true but the reason is false D Both assertion and reason are false statements

Which one of the following was concluded from Rutherford s alpha particle scattering experiment A Electrons have negative charge B Most of the space in atom is empty Neutron exists in the nucleus D Alpha particles are four times as heavy as a hydrogen atom

3B The distribution coefficient of Caffeine in the methylene dichloride water solvent system is 4 6 a In which solvent is caffeine more soluble Ans b Caffeine in the amount of 2 mg is dissolved in 100 mL of water Following the same procedure as that for benzoic acid 100 mL of methylene dichloride is used instead of 600 L how many

16 Which alum is a double salt made up of two salts 1 Salt of a SA WB Salt of a WA WB 3 Salt of a SA SB Salt of a WA WB 2 Salt of a SA SB Salt of a SA WB 4 Salt of a SA WB Salt of a WA WB

vii A living cell contains a solution which is isotonic with 0 3 M sugar solution x 05 What osmotic pressure develops when 20 the cell is placed in 0 1 M KCl solution at body temperature al a 5 08 atm b 2 54 atm d 2 46 atm viii The osmotic pressure of blood is 7 65 MRT olxo 082 4 92 atm

A chemical reaction proceeds into the following steps Step 1 2A X fast Step II X B Y slow Step III Y B Product fast The rate law for the overall reaction is 1 Rate K A 3 Rate K A B 2 Rate K B 4 Rate K A B

The half life period of a gaseous substance undergoing thermal decomposition was measured for various initial pressure P with the following result P mm 5250 6300 11 2 min 136 112 5 Calculate the order of the reaction

Q 51 The specific rate constant of the 1 decomposition of N O5 is 0 008 min The volume of O collected after 20 minutes is 16 ml The volume that would be collected at the end of reaction NO formed is dissolved in CCI ml

The ionization energy of He is 19 6 10 18 J per atom Phe energy of the second stationary state in Li2 ion will be 214 4 9 10 18 44 1 x 10 18 J A C TITL B D 2 18 10 18 J 11 025 x 10 8 J

Ez explain all the options al solution to FeCl solution 18 Dimer of acetic acid in benzene is in equilibrium with acetic acid at a particular condition of temperature and pressure If half of the dimer molecules are hypothetically separated out then 1 Osmotic pressure of the solution reduces 2 Freezing point of the solution reduces 3 Boiling point of the solution reduces 4 Vapour pressure of the solution reduces All th

Ans is c option 7 How long approximate should water be electrolysed by passing through 100 amperes current so that the oxygen released can completely burn 27 66 g of diborane Atomic weight of B 10 8 a 6 4 hours b 0 8 hours c 3 2 hours 2018 Main d 1 6 hours

59 The solubility of a salt A B in pure water will be Ksp of A B 1 08 10 6 1 3 x 10 6 mol L 1 3 4 10 2 mol L 1 60 The oxidation state of Cr in CrO is 2 2 x 10 8 mol L 1 4 3 x 10 18 mol L 1

The volume of air needed for complete combustion of 1 kg carbon at STP is 1 9333 3 litre 2 933 33 litre 3 93 33 litre 4 1866 67 litre

Q 43 The enthalpy change states for the following processes are listed below Cl g 2C1 g 242 3 kJ mol 1 g 21 g 151 kJ mol 1 ICI g I g Cl g 242 3 kJ mol 1 s 1 g 62 76 kJ mol 1 on Given that the standard states for iodine chlorine are 1 s and Cl g the standard enthalpy of formation for ICI g is 1 244 8 kJ mol 1 2 14 6 kJ mol 1 3 16 8 kJ mol 1 4 16 8 kJ mol 1

The correct statement on the aufbau principle is that n 1 d subshell is always lower in energy than ns orbital B n 1 f subshell is always has energy more than np orbital 5d is lower in energy than 4f X 6p is lower in energy than 5d C D 4

CAREER INSTITUTE KOTA RAJASTHAN In BF3 the B F bond length is 1 30 when BF3 is allowed to be treated with Me N it forms an add Me N BF3 The bond length of B F in the adduct is 1 Greater than 1 30 4 None of these 2 Smaller than 1 30 3 Equal to 1 30

In concentration cell Fe Fe2 C Fe C Fe for spontaneous cell reaction C C AG 0 C C AG 0

2 For the reaction N 3H 2NH3 the rate of change of concentration for hydrogen is 0 3x10 Ms 1 The rate of change of concentration of ammonia is 1 0 2 104 2 0 2 x 10 4 3 0 1 10 4 4 0 3 x 10 4

Experimentally it was found that a metal oxide has formula Mo 980 Metal M is present as M and M in its oxide Fraction of metal 3 3 which exists as M is 1 4 08 3 5 08 2 6 05 4 7 01

2X g Y g Z g The equilibrium concentration of X g Y g and Z g are respectively 4 2 and 2 M How man moles of X g is to be added so that the concentration of Y g becomes 3M at the new equilibrium

In a reaction the initial concentration of the reactants increase four fold and the rate becomes eight times its initial value The order of the reaction is X ther value of 10 X is If the reaction is A B and elementary

27 The reaction of hydrogen and iodine monochloride is given as H2 g 21Cl g 2HCl g 2 g This reaction is of first order with respect to H2 g and ICI following mechanisms were proposed Mechanism A H2 g 21Cl g 2HCl g 2 g Mechanism B H2 g ICI g HCl g HI g slow HI g ICI g HCl g 12 g i fast COLS Which of the above mechanism s can be consistent with the given information about the AIPMT Prelims 2007 reaction 1 A only 2 B only 3 Both 1 and 2

Which of the following nuclear reactions will generate an isotope 1 Neutron particle emission 2 Positron emission 3 a particle emission 4 particle emission

Assuming complete ionization same moles of which of the following compounds will require the least amount of acidified KMnO4 for complete oxidation Re AIPMT 2015 A FeC 04 B Fe NO2 2

7 What is the ratio of time periods T T in second orbit of hydrogen atom to third orbit of He ion 1 8 27 3 27 32 2 32 27 4 None of these

if the Ecell for a given reaction has a negative value then which of the following gives the correct relationship for the values of AG and Keq 1 AG 0 K 1 3 AG 0 Keq 1 44 AG 0 Ke 1 2 AG 0 Keq 1

3 5 44 x 10 19 Cal 4 5 44 x 10 19 erg 0 5 g particle has 2 x 10 m uncertainity in position find the uncertainty in its velocity m s 1 3 0 x 1033 2 5 x 10 27 3 4 x 10 30 4 4 x 10 10

In view of the signs of A G for the following reactions PbO Pb2 Pb0 4G 0 SnO Sn 2 SnO 4 G 0 Which oxidation states are more characteristic for lead and tin 1 4 2 respectively 3 4 4 respectively 2 2 2 respective 4 2 4 respective

DA KA Ag and A are the concentration at time t 0 and t respectively If 10 min were required for A to become dt in min is For a reaction with rate equation required to become A the time