Physical Chemistry Questions

MY and NY two nearly insoluble salts have the same Ksp values of 6 2 x 10 13 at room temperature Which statement would be true in regard to MY and NY NEET 2016 1 The addition of the salt of KY to solution of MY and NY will have no effect on their solubilities 2 The molar solubilities of MY and NY in water are identical 3 The molar solubility of MY in water is less than that of NY 4 The salts MY and NY are more soluble in

One quantum is absorbed per gaseous molecule of X for converting it into X atoms If light absorbed has wave length 1240A then bond energy of X will be 1 10 eV molecule 2 20 J mole 3 48 eV molecule 4 184 J mol

Consider the following liquid vapour equilibrium 2016 Liquid Vapour Which of the following relations is correct denP AH b dT RT a c denG AH dT RT2 denP dr AH T d denP dT AH RT

The figure below is the plot of potential energy versus inter nuclear distance d of H molecule in the electronic ground state What is the value of net potential energy E as indicated in figure in KJ mol for d d at which the electron electron repulsion and the nucleus nucleus repulsion energies are absent As reference potential energy of H atom is taken as ZERO when its electron and nucleus are infinitely far apart NA 6 023 x 102 mol lith Eo Potential Energy k mol d H do Internuclear distance d

Jane has developed an equation relating cholesterol levels to hours of exercise hours in the sunlight and protein food consumed Bill has an idea that when there are many rainy days cholesterol levels are low and Tom has found that more days in the gym and dietary fat consumed relate to cholesterol levels but he hasn t quantified his data Who is proposing a hypothesis who a theory and who a law O Jane and Bill hypotheses Tom a theory O Bill a law Jane a theory and Tom a hypothesis O Jane a law Tom a theory and Bill a hypothesis Jane a theory Tom a hypothesis and Bill a law

2 57 Graph between log x m and log p is straight line inclined at an angle of 45 When pressure is 0 5 atm and 1k 0 693 the amount of solute adsorbed per gm of adsorbent will be

3 Adding pressure to a closed half full bottle of water will cause a more of the liquid water to evaporate into the gaseous space b more of the water vapour in the gaseous space to condense into liquid wate C no change in the amount of water vs water vapour d the temperature of the water to decrease

If the mole fraction of solute in an aqueous solution is changed from the ratio of initial and final molality of solute in the solution is A 1 1 B 2 1 C 3 1 D 4 1 1 2 to 114 by adding water then

N At 298 K in a constant volume calorimeter 0 01 mole of TNT was detonated when 8180 cals of heat was released Each mole of TNT gives 6 moles of gaseous products on detonation What is AH mole of TNT exploded H

5 Which of the following is incorrect 1 Mass of the gas dissolved in liquid depends upon pressure of gas 2 Volume of the gas dissolved in liquid depends upon pressure applied 3 Value of K decreases on increasing temperature 4 Both 2 3

AB crystal is formed when B ion occupies ccp arrangement while A ion occupies all the octahedral sites Total number of ions present in one unit cell when all ions along one of the body diagonal plane are removed will be 1 3 5 2 2 5 4 7 2

Since right hand side does not contain concentration term hence time taken for the completion of any fraction first order reaction is independent of initial concentration of the reactant Example 13 A first order reaction is 50 complete in 100 minutes How long will it take for 90 completion

The vapour pressure of pure X are given by the following equation Sold X In P mm of Hg 10 3000 K T Liquid X In P mm of Hg 5 1800 K T Find out the freezing point of X 200 K 220 K 240 K 273 K

2 58 Fixed amount of an ideal gas contained in a sealed rigid vessel V 24 6 litre at 1 0 bar is heated reversibly from 27 C to 127 C The change in Gibb s energy is J AG in Joule if entropy of gas S 10 10 T J K

Problem 8 10 Permanganate VII ion MnO4 in basic solution oxidises iodide ion I to produce molecular iodine 1 and manganese IV oxide MnO Write a balanced ionic equation to represent this redox reaction

14 2 g Na SO4 was dissolved in X gm of H O The change in freezing point was found to be 3 82 C If Na2SO4 is 90 ionized the value of X Kf for water 1 86 C kg mol M Wt of Na SO4 142 g mol 1 1 363 g 2 0 1363 g 3 13 63 g 4 126 22

4 5 27 79 The increase in rate constant when its temperature is raised from 300 K to 320 K if activation energy for the reaction is 10 kcal mole is 2 81 8 8 58 1 100 3 183 3

6 Why is it important to neutralize the basic solution the one that contains the acid unknown to pH 3 Instead of just pH 7 Why is the acidic solution containing the basic unknown neutralized to pH 11 or greater To answer this question you will need to discuss pka s of the compounds

70 The equilibrium constant of the reaction Zn Hg HgO s ZrO s Hg 1 having E 1 55 volt at 298 Kis 1 2 8 x 1052 3 3 5 x 1070 2 2 8 x 1040 4 3 5 1035

4x10 moles of a non volatile solute is added into 10 moles of solvent The solute polymerises into a soluble solid following first order kinetic with a rate constant equal to 0 693 min If after 2 min elevation in boiling point is observed to be 0 01 C then calculate which form the solute is getting polymerized into Given Molar mass of solvent 100 g mole K of solvent 0 5 K kg mol Instruction Mark 2 if polymer is dimer 3 if trimer and so on YOUR ANSWER D 2

Which of the following is are correct for the reaction with equilibrium constant K A g B g c g D g AH 20 J 1 2 3 rrect Answer 1 2 3 kt Keq will increase on increasing temperature kt will increase on increasing temperture kb will increase on increasing temperature kb will decrease on increasing temperature

for which of the following processes reaction entropy change is negative A Stretching of rubber band B C D Boiling of egg BaCl Na SO BaSO 2NaCl aq q ppt aq Dissociation of 1 mole of dihdyrogen gas into

78 What is pH of the resulting solution when 100 m of 0 1 M NaOH is mixed with 100 ml of 0 1 M CH COOH PK for CH COOH 4 76 1 8 73 3 8 58 2 7 38 4 5 27

The reaction 24 g B g 3C g D g is begun with the concentrations of A and B both at an initial value of 1 00 M When equilibrium is reached the concentration of D is measured and found to be 0 25 M The value for the equilibrium constant for this reaction is given by the expression 2010 a 0 75 0 25 0 75 0 25 b 0 75 3 0 25 1 00 1 00 c 0 75 0 25 0 50 0 75 3 10 051 050 025

Boiling point or freezing point of liquid solution would be affected by the dissolved solids in the liquid phase A soluble solid in solution has the effect of raising its boiling point and depressing its freezing point The addition of non volatile substances to a solvent decreases the vapor pressure and the added solute particles affect the formation of pure solvent crystals According to many researches the decrease in freezing point directly correlated to the concentration of solutes dissolved in the solvent This phenomenon is expressed as freezing point depression and it is useful for several applications such as freeze concentration of liquid food and to find the molar mass of an unknown solute in the solution Freeze concentration is a high quality liquid food concentration method where water is removed by forming ice crystals This is done by cooling the liquid food below the freezing point of the solution The freezing point depression is referred as a colligative property and it is proportional to the molar concentration of the solution m along with vapor pressure lowering boiling point elevation and osmotic pressure These are physical characteristics of solutions that depend only on the identity of the solvent and the concentration of the solute The characters are not depending on the solute s identity I 1 When a non volatile solid is added to pure water it will a boil above 100oC and freeze above 0oC b boil below 100oC and freeze above 0oC c boil above 100oC and freeze below 0oC d bail below 1000f and freeze below 000

Which of the following compounds can be used to obtain free nitrogen A NH4NO B HNO2 C HNO3 D Ba3N Solution A NH4NO ammonium nitriteis the only convenient compound that can be used to obtain fre nitrogen even in laboratories NH Cl aq NaNO aq NH4NO aq NaCl aq By heating ammonium nitrite A NH NO g No a 2H O 1

Q 33 Calculate the ground state energies of the 2 electron in eV in the case of He and Li RH 13 6 eV 1 13 60 eV and 54 40 eV 2 54 40 eV and 13 60 eV 3 54 40 eV and 122 40 eV vom 4 13 60 eV and 122 40 eV

2 56 An organic liquid A is immiscible with water When boiled together with water the boiling point is 90 C at which the partial vapour pressure of water is 526 mm Hg The atmospheric pressure is 736 mm Hg The weight ratio of the liquid and water collected is 2 5 1 The molecular weight of the liquid

3 Assume three samples of juices A B and C have glucose as the only sugar present in the The concentration of sample A B and C are 0 1M 5M and 0 2 M respectively Freezing point will be highest for the fruit juice a A b B c C d All have same freezing point

13 Which of the following statements is false 1 point O 1 Two different solutions of sucrose of same molality prepared in different solvents will have the same depression in freezing point ii The osmotic pressure of a solution is given by the equation CRT where C is the molarity of the solution iii Decreasing order of osmotic pressure for 0 01 M aqueous solutions of barium chloride potassium chloride acetic acid and sucrose is BaCl2 KCI CH3COOH sucrose iv According to Raoult s law the vapour pressure exerted by a volatile component of a solution is directly proportional to its mole fraction in the solution

Concentrated aqueous sulphuric acid is 98 H SO4 by mass and has a density of 1 80 gmL 1 Volume of acid required to make one litre of 0 1 M H SO4 solution is 116 65 mL 2 22 20 mL 3 4 O 5 55 mL O 11 10 mL

How many grams of concentrated nitric acid solution should be used to prepare 250 mL of 2 M HNO3 The concentrated acid is 70 w w HNO3 NEET 2013 1 90 0 g conc HNO3 2 70 0 g conc HNO3 3 54 0 g conc HNO3 4 45 0 g conc HNO3 21

Kunal a class 10 student studied the reaction between marble chips and dilute HCI He took 50 g of marble chips and 100 mL of 0 1 molar HCI solution The given graph shows how the total mass PO Time min of marble chips varies with time as the reaction proceeds Which of the following statements are incorrect More and more CO gas is evolved along PQ CaCO remains unreacted after point P Reaction gets completed at point P Dilute HCI remains unreacted after point P B II and III only D II III and IV only I II III IV A C I and IV only I II and IV only Mass of CaCO

Standard potentials E for some half reactions are given below 1997 2 1 Sn 2e Sn E 0 15 V 2 2 Hg 2e Hg 2 E 0 92 V 3 PbO 4H 2e Pb 2H O E 1 45 V Based on the above which one of the following statements is correct a Sn4 is a stronger oxidising agent than Pb4 b Sn is a stronger reducing agent than Hg 2 c Hg2 is a stronger oxidising agent than Pb4 d Pb2 is a stronger reducing agent than Sn

Chemists classify material as heterogeneous or homogenebus and some homogeneous materials as pure substances Which of these are pure substances Gold and salt solutions Salt solutions and coal Sodium chloride and matures of sodium and potassium Gold and sodium chloride

2 1 The moles of electrons required to deposit 1 gm equivalent aluminium at wt 27 from a solution of aluminium chloride will be Anonymous Quiz 51 3

Given that E 2 F6 0 44VE 2 Fe3 0 77V if Fe Fe3 and Fe solid are kept together then Fest increases Fest decreases Fe Fest remain unchanged Fert decreases 2 3 4 brrect Answer 2 atus

Q 58 Fixed amount of an ideal gas contained in a sealed rigid vessel V 24 6 litre at 1 0 bar is heated reversibly from 27 C to 127 C The change in Gibb s energy is J AG in Joule if entropy of gas S 10 10 T J K

1 a what is the mass of NaNO3 required to make 50 00 mL of a 0 1500 M solution b find absolute uncertainty in the molar mass of NaNO3 c Calculate the absolute uncertainty in the concentration assuming that the balance is precise to 0 1 mg and that the volumetric flask is calibrated and precise to 0 05 mL Please provide all the steps as well as the correct number of significant figures

20 Assertion Semiconductors are solids with conductivities in the intermediate range from 10 6 104 ohm 1m 1 Reason Intermediate conductivity in semiconductor is due to partially filled valence band O C

bo a IU c 20 14 g 001 21 zaobusd d 40 bsd to 101 70 A compound possesses molecular mass is 80 1 6 a 200 c 155 8 sulphur by mass The b 400 d 355 1 Equivalent weight of I in the reaction 7 1 5Cl 6H O 2HIO3 10HC1 is a M c M 5 b M 2 d M 10

A Assertion and reason both are correct statements and reason is correct Explanation for assertion B Assertion and reason both are correct statements but reason is not correct explanation for assertion C Assertion is correct statement but reason is wrong statement D Assertion is wrong statement but reason is correct statement 16 Assertion The total number of atoms present in a simple cubic unit cell is one Reason Simple cubic unit cell has atoms at its corners each of which is shared between eight adjacent unit cells O A B D

WORKED OUT EXA EXAMPLE 19 Calculate AH for the reaction CH g 4F g CF g 4HF g Given that the enthalpies of formation of CH CF and HF are 75 kJ 680 kJ and 269 kJ respectively SOLUTION YAH Reactants

7 The edge length of a unit cell of a metal having molecular mass 75 g mol is 5A which crystallises in a cubic lattice If the density is 2 g cc then find the radius of metal atom 8 a State Rault s law and Show that relative lowering in vapour pressure ids equal to mole

Network solids are distinguished from metallic crystals in the fact that a Network solids have charged ions while metallic crystals do not b Network solids are composed of molecules while metallic crystals only have one type of ato c Network solids are composed of non metals d Network solids have much lower melting points

Q 59 The following sequence of reaction occurs in commercial production of aqueous nitric acid 4NH3 g 5O g 4NO g 6H O l AH 904 kJ 1 2NO g O g 2NO g BAD HOOD DH 1 AH 1124 kJ 2 HOO 3NO g H O 1 2HNO3 aq NO g D you AH 140 kJ 3 banka The total heat liberated in kJ at constant pressure for the production of exactly 1 mole of aqueous nitric acid by this

12 In comparison to a 0 01 M solution of glucose the depression in freezing point of a 0 01 M MgCl2 solution is i the same O ii about twice O iii about three times O iv about six times

5 Which of the following is correct for CaF2 unit cell les 1 Co ordination number of Ca is 8 2 F occupies 100 tetrahedral void id g9014 CONS 3 Mass of unit cell will be 4 times mass of CaF 2 4 All of these

Correct statement s a At midway in the transition of an acidic indicator pH pk In b Methyl orange 3 1 to 4 4 is a suitable indicator for titration of weak acid and strong ba c Bromothymol blue 6 0 to 7 6 is a good indicator for titration of HCl and NaOH d Thymol blue 1 2 to 2 8 is a very good indicator for titration of 100 mL of 0 1 MNF pK 4 74 and 0 1 M HCl b ach titrated

Which of the following statement is correct A In the unit cell of rhombic Sulphur the axial distances are equal and the v of each axial angle is 90 B Amorphous solids are anisotropic in nature C Silicon doped with Arsenic impurity is a p type semiconductor D In MnO all the domains are aligned in the same direction