Physical Chemistry Questions

You want to determine the accuracy of your analytical method You purchase a certified sample that contains 17 3 ppm of your analyte You measure the concentration in this sample three times and obtain concentration values of 15 4 15 2 and 15 6 ppm What is the absolute accuracy of your analysis

Assignment Set 2 49 H S gas when passed through a solution of cations containing HCI precipitates the cations of second group of qualitative analysis but not those belonging to the fourth group It is because AIPMT Prelims 2005 1 Presence of HCI decreases the sulphide ion concentration 2 Presence of HCI increases the sulphide ion concentration 3 Solubility product of group Il sulphides is more than that of group IV sulphides 4 Sulphides of group IV cations are unstable in HCI ol Answor 1

i PCI g PCI g Cl g and ii SO CI g So g Cl g are simultaneously in equilibrium in an equilibrium box at constant volume A few moles of PCI C are later introduced into the vessel After som time the new equilibrium concentration of 1 SO Cl will remains unchanged 2 Cl will be greater 3 SO Cl will become less A SO CL will become greater

d The Pd isotope has a half life of 23 4 minutes If you have 5 000 kg of Pd when you start to take the Final Exam what mass of Pd in grams will you have two hours and 45 minutes later when you turn in your answers to the Final Exam on Canvas

Pbo PbS T t 16 Galena an ore is partially oxidized by passing air through it at high temperature After some time the passage of air is stopped but the heating is continued in a closed furnace such that the 2018 contents undergo self reduction The weight in kg of Pb produced per kg of O2 consumed is Atomic weights in g mol 1 O 16 S 32 Pb 207

An ideal gas is expanded from p V T to P2 V T under different conditions The correct statement s among the following is are Question Type Multiple Correct Type 1 2 3 4 The work done on the gas is maximum when it is compressed irreversibly from P2 V to P V against constant pressure p The work done by the gas is less when it is expanded reversibly from V to V under adiabatic conditions as compared to that when expanded reversibly from V to V2 under isothermal conditions The change in internal energy of the gas i zero if it is expanded reversibly with T T and ii positive if it is expanded reversibly under adiabatic conditions with T T2 If the expansion is carried out freely it is simultaneously both isothermal as well as adiabatic

Chemistry Question No 54 Question Palette The minimum volume of 20 volume H O solution that decolourises 200 mL of 2N KMnO solution in acidic medium is

Salt bridge A concentration cell similar to the one shown is composed of twa Ph electrodes and solmons of different Pb2 concentrations The left compartment contains 1 25 M Ph and t compartment contains 2 26 162 Ph Calculate the cell potential for this reaction at 298 K volly

When 1 0 kg of anthracite coal is burned about 7300 kcal is evolved What amount of coal is required to heat 4 0 kg of water from room temperature 20 C to the boiling point at 1 atm pressure assuming that all the heat is available 320 g 32 g 44 g 440 g

Give reasons for your answer KF crystallizes in the NaCl type structure If the radius of K ions 132 pm and that of F ion is 135 pm what is the shortest K F distance What is the edge length of the unit cell What is the closel K K distance

The density of a poure substance A whose atoms pack in cubic close pack arrangement is I gm cc If B atoms can occupy tetrahedral void and if all the tetrahedral voids are occupied by B atom What is the density of resulting solid in gm cc Atomic mass A 30 gm mol Atomic mass B 50 gm mol dezay 120 A 3 33 B 4 33 520 C 2 33 ev V D 5 33

Consider the following adsorption isotherms for amount of adsorption versus pressure m 31x m 1 P 3 P XE m X m 5 2 PO 4 P P Identify the curves which are showing adsorption in multimolecular layer If the total number of curves as per the question is p then the value of p is

b Air 79 mol nitrogen and 21 mol oxygen is passed over a catalyst at high temperature Oxygen completely reacts with nitrogen as shown below 0 5 N2 g 0 5 02 g NO g 0 5 N2 g O2 g NO2 g The molar ratio of NO to NO2 in the product stream is 2 1 What is the fractional conversion of nitrogen C One mole of methane undergoes complete combustion in a stoichiometric amount of air The reaction proceeds as CH4 202 CO2 2H2O Both the reactants and products are in gas phase AH 298 730 kJ mole of methane If the average specific heat of all the gases vapor is the maximum temperature rise of the exhaust gases in OC would be approximately equal to Assume the reference temperature 298 K 40 J mol K 1

2 42 In the Bohr s model for unielectronic species following symbols are used Radius of nth orbit with atomic number z Potential energy of electron in nth orbit with atomic number z Kinetic energy of electron in nth orbit with atomic number z Velocity of electron in nth orbit with atomic number z Time period of revolution of electron in nth orbit with atomic number z Calculate z in all cases 1 1 z U 2 K 2 8 1 iii V1 2 V3 1 9 1 Inz U 11 z K n Z V z T n z 1 212 1 1 8 T1 2 T2 2 9 32 Represent your answer as abcd where a b c and d represent number from 0 to 9 a b cc represents the value of z in parts i ii iii iv Suppose your answer is 1 2 3 4 th same must be filled in OMR sheet as1234 00

a When we talked about bonding in metals I mentioned that solid metals like ionic compounds can have structures based on the placement of the metal atoms in unit cells Palladium for example has a face centered cubic unit cell structure How many palladium atoms are contained in one mole of palladium unit cells Sketch a unit cell for metallic Pd

Problem No 30 Find the spectral terms of np electrons and compare the results obtained with t spectral terms obtained using Breit s scheme Write the spectral terms in the order the increasing energy values

Enthalpy of the reaction 1 O g CH OH is negative I 2 enthalpy of combustion of CH3OH 1 and CH4 g a and b respectively then select the correct relationship are 1 a b 3 a b CH4 g 2 a b 4 a b

The potential energy W of a system of two atoms A B varies as a function of their distance of separation r as follows The bond dissociation energy of A B bond DA B is given by A 1 DA B 2 DA BE 3 DA B 4 DA B A A m n n 1 m n

Following diagrams show identical cubes such that edge of cube2 lies exactly in the middle of one of the faces of Cube1 and Cube 4 has a corner at the body center of the Cube3 Find the contributions in fraction of the spheres shown to each of the cubes B Atom 27 3 Atom

THE CORRECT ANSWER 9 A Daniel Cell may be represented as Zn s Cu2 aq Zn2 aq Cu s If AG 293 formation 0 for Zn s and Cu s 35 14 Kcal mol for Zn aq and 15 66 Kcal mol for Cu 2 aq calculate the E for the cell and equilibrium constant of the reaction under standard condition

208 Equilibrium Solution of Assignment Set 2 11 The Ksp of Ag CrO4 AgCl AgBr and Agl are respectively 1 1 x 10 12 1 8 x 10 10 5 0 10 13 8 3 10 17 Which one of the following salts will precipitate last if AgNO3 solution is added to the solution containing equal moles of NaCl NaBr Nal and Na CrO4 AIPMT 2015 1 Ag CrO 3 AgCl Sol Answer 1 2 4 Agl AgBr

P3 P4 P3 P4 e is inversely ance between magnitude cles 10 Atmospheric pressures recorded in different cities are as follows Cities Shimla p in N m2 1 01 105 Bangalore Delhi Mumbai 1 2x105 1 02x105 1 21 105 Consider the above data and mark the place at which liquid will boil first a Shimla c Delhi b Bangalore d Mumbai Intermolecular 11 Wii Poulve rattraction represents the curve of Notfas So for a is F en lin Fough t

v Cryoscopic constant depends on nature of solvent b nature of solute c nature of solution A number of solvent molecules

In a galvanic cell Cu is reacting with nitric acid to produce NO or NO At what NO3 tendency of formation of NO NO is same E Cu Cu E 0 34V NO NO H E 0 79V 0 96V NO NO H Assume pressure of all the gases are taken as unity P NO PN NO

ABC A cubic solid is made up of two elements A and B Atoms B are at the corners of the cube and A at the body centre What is the formula of compound 74 FCC N 4 A cubic solid is made by atoms A forming close pack arrangement B occupying one Fourth of tetrahedral istryP3 E03 Sold Se

Consider the four statements below Which of these best describes a theory A statement of a possible explanation for observed phenomena D A procedure for making controlled observations An explanation that is trusted because repeated tests have confirmed its validity d A summary of observed regularity in nature often as a mathematical equation

An element crystallizes into a structure which may be described by a cubic type of unit cell having one atom on each corner of the cube and two atoms on one of its body diagonals If the volume of this unit cel a is 24x10 24 cm and density of element is 7 2 g cm calculate the number of atoms present in 200 g o element

A polyvalent metal weighing 0 1 g and atomic weight 51 reacted with dil H SO4 to evolve 43 9 ml of H2 at STP This solution containing metal in lower oxidation state was found to require 58 8 ml of 0 1 N permanganate for complete oxidation Identify the higher oxidation state of the metal A 2 C 5 B 3 D 7

A crystal of lead II sulphide has NaCl structure In this crystal the shortest distance between Pb 2 ic and S ion is 297 pm What is the length of the edge of the unit cell in lead sulphide Also calculate th unit cell volume

What is the energy change when 25 0 g of water is cooled from vapor at 100 0 C to liquid water at 40 0 C Water H O Physical Data Molar Mass 18 02 g mol Enthalpy of Vaporization AHvap 40 7 kJ mol Specific Heat C 4 184 J g C 1 O 6 27 kJ O 6 27 kJ O 62 7 kJ

a 46 g b 20 g 7 The total no of neutrons present in 54 mL H O I are c 24 N a 3 NA b 30 NA 8 Total no of electrons present in 48 g Mg2 are A d none of these d non of these

12 What is the percent by mass of titanium in rutile a mineral that contain Titanium and oxygen if structure can be described as a closet packed array of oxide ions with titanium in one half of the octahedral holes What is the oxidation number of titanium Ti 48

O The interaction energy of London force is inversely proportional to sixth power of the distance between two interacting particles but their magnitude depends upon a charge of interacting particles b mass of interacting particles c polarisability of interacting particles d strength of permanent dipoles in the particles De dipol for CA Abween tele possessing permanent dipole Ends of lipoles posses partial charges Thertial charge is ha un lectronic charge a myri tec b equal to unit electronic charge

ate the interionic d pm The density of KBr is 2 75 g cm3 The length of the edge of the unit cell is 654 pm Find the nu fomula unit of KBr present in the single unit cell N 6 023x1023 mol At mass K 39 Br 80

The compound nickel II acetate is a strong electrolyte Write the reaction when solid nickel II acetate is put into water

A closed vessel with rigid walls contains 1 2 mol of 23892U and 1 mol of air at 298 K Considering complete decay of 23892U to 20682Pb the ratio of the final pressure to the initial pressure of the system at 298 K is uestion Type Numerical Type

M The equivalent conductance of 10 Given A HA 80 ohm cm eq 2 5 x 10 4 3 5 10 3 6 5 x 10 4 5 5 10 5 solution of a weak monobasic acid HA is 4 ohm cm eq The dissociation constant of the acid will be

hic gas is higher than that of a monoatomic gas Heat Ca Multiple Choice Questions with ONE correct answer 1 The standard state Gibbs free energies of formation of C graphite and C diamond at T 298 K are 1985 A G C graphite 0 kJmol A G C diamond 2 9 kJmol The standard state means that the pressure should be 1 bar and substance should be pure at a given temperature The conversion of graphite C graphite to diamond C diamond reduces its volume by 2 x 10 6 m mol If C graphite is converted to C diamond isothermally at T 298 K the pressure at which C graphite is in equilibrium with C diamond is Useful information 1 J 1 kg m s 2 1 Pa 1 kg m s 2 1 bar 105 Pa A 14501 bar C 1450 bar B 58001 bar D 29001 bar 2017

6 Consider the following liquid vapour equilibrium Liquid Vapour Which of the following relations is correct 3 dinP AH dT RT2 dinP AH Sol Answer 1 RT 2 4 dinG AH dT RT dinP dT AH T Equilibrium 201 NEET 2016

2 Decreased 3 Remains constant 4 May increased or decreased depends on exothermic or endothermic nature What will be the equilibrium constant at 127 C If equilibrium constant at 27 C is 4 for reactic N 3H 2NH AH 1 4 x 10 46 06 kJ 2 2 x 10 3 3 10 4 4 10

12 Two closed bulbs of equal volume V an ideal gas initially at pressure p and temperature T are connected through a narrow tube of negligible volume as shown in the figure below The temperature of one of the bulbs is then raised to T The final pressure pf is is T T T Pi V P V T T T T Pf V T Pf V T T T b 2pi 14 20 72 7 d Pi a Pi 2Pi 4 27 7 7 here no of mole Mair T T ideal gas is incre

8 for the reaction at 500K 2A g B g C g AH 300 Kcal mol4moles of A and 3 moles of B are taken Value of heat change at constant volume on completion of reaction will be 1 299 Kcal mol 3 598 Kcal mol 2 596 Kcal mol 4 301 Kcal mol

Identify the correct order of solubility in aqueous medium 1 ZnS Na S CuS Sol Answer 3 NEET 2013 2 Na S CuS ZnS 3 Na S ZnS CuS 4 CuS ZnS Na S

The polymerization of terephtalic acid and ethylene glycol is self catalyzed and carried out at 290 C The rate constant k is 2 65 105 dm5 s mol The monomers are added to the batch reactor in stoichiometric amounts a If we would like to produce PET with a number average molecular weight of 2 500 g mol within 7 hours what initial concentration of the monomers is needed

What is an example of useful work 1 Electricity generation from solar cells used to power electric motors 2 Expansion of a vessel due to creation of gas in a chemical reaction 3 Contraction consumption 4 A system at equilibrium of a vessel due to gas in a chemical reaction

Osmotic pressure of a solution containing 2 g dissolved protein per 300 cm of solution is 20 mm of Hg at 27 C The molecular mass of protein is a 6239 6 g mol c 3692 1 g mol 1 b 12315 5 g mol 1 d 7368 4 g mol 1

What is the necessary condition for the existence of solids a Intermolecular forces should be weaker than thermal energy b Intermolecular forces should be stronger than thermal energy c Intermoiecufar forces should be equal to the thermal energy d No definite relationship between them in the figure

How many e are left over on the central atom of H SeS4 what is the formal charge fc on the central atom 2e 1 left over fc O 0 e 1 left over fc 0 0 e left over fc 1 O e 1 left over fc 2

If the length of the body diagonal for CsCl which crystallises into a cubic structure with Clions at the corners and Cs ions at the centre of the unit cells is 7 and the radius of the Cs ion is 1 69 what is the radii of CI ion

17 he number of atoms present in 200 g of The two ions A and B have radii 88 and 200 pm respectively In the closed packed crystal of compound AB predict the co ordination number of A