Physical Chemistry Questions

31 4 grams of NaOH are transferred to 100mL of 1M H SO solution Calculate the pH of Ans zero 4 the final mixture

At 47 C the vapour pressure of pure ethyl bromide C H Br is 10 Torr and that of pure ethyl chloride C H Cl is 40 Torro Assuming ideal behaviour mole fraction of C H Cl in the liquid state is A 0 20 D 0 25 OUE EN B 0 50 and liathy A C 0 75

The freezing point of a dilute solution of acetamide in glacial acetic acid is 298 K This is the value when crystals of 1 ice first appears acetic acid first appears 2 acetamide first appears 4 both appear together

V2 V2 Pav RT d nRT dv P nRT V V V As the process is isothermal so Tremains constant Wrev Wrev nRT 1 V 2 j dv V1 TZ

Maximum deviation from ideal gas is expectec from NEET 2013 1 N g 2 CH g 3 NH 9 4 H g

When mercuric iodide is added to the aqueous solution of potassium iodide then Freezing point is increased Boiling point is increased 3 Freezing point does not change 4 Boiling point does not change

11 Methanol and C H OH form an ideal solution Solution is prepared by mixing 32 gm of CH C and 23 gm of C H OH at 300K At 300K Po 90 mm of Hg and Po 51 mm of Calculate methanol ethanol S i partial vapour pressure of its constitutents and total vapour pressure of solution ii Mole fraction of each component in vapour phase

11 Ionization energy for hydrogen atom in ergs Joules and eV respectively is Inqining b 13 6 x 218 10 20 21 8 10 3 RECO d 21 8 x 10 3 13 6 21 8 10 20 218 10 20 13 6 a 21 8 x 10 2 218 10 c 21 8 10 20 13 6 21 8 x 10 13

An aqueous solution contains an unknown concentration of Ba When 50 mL of a 1 M solution of Na SO4 is added BaSO4 just begins to precipitate The final volume is 500 mL The solubilit product of BaSO is 1 x 10 What is the original concentration of Ba 10 M 1 1 0 10 10 3 2 10 M 2 5 x 10 M 4 1 1 x 109 M MAINS 2018

When same quantity of electricity is passed the electrochemical equivalents of the two metals liberated at the electrodes have the same ratio as that of their a atomic masses c equivalent masses b molecular masses d any of the three

2 AH of water is 285 8 kJ mol If enthalpy of neutralization of strong monoacid with strong mono 57 3 kJ mol AH of OH ion will be 228 5 kJ mol 1 3 114 25 kJ mol 1 2 228 5 kJ mol 1 4 114 25 kJ mol 1

the iii A compound on analys is shows C 40 H 6 67 and 0 53 33 Determine empirical formula of the compound If molar mass of the compound is 30g mol 1 what is its molecular mass 1 1

49 A gaseous hydrocarbon gives upon combustion 0 72 g of water and 3 08 g of CO2 The empirical formula of the hydrocarbon is

Molarity of NaOH in 200 mL of an aqueous solution of it is 1M find the change in molarity if 2g of NaOH is added to it 1 1 25 M 3 0 50 M 2 0 25 M 4 0 75 M

The volume and temperature of 2 mol of an ideal gas are 10L 27 C respectively The gas is allowed to expand in an isothermal reversible process to attain final volume of 25 L Calculate the maximum work a done Ans We know that maximum work is obtained in a reversible isothermal expansion Now work done by an ideal gas in an isothermal V reversible expansion w nRT In V Given n 2 T 273 27 300K V 10 L V 25L w 2x 8 314 x 300 In 25 J 4570 82 J 10 The maximum work done by the gas 4570 82 J

Oxalic acid H C O4 reacts with permanganate ion according to the balanced equation below How many mL 0 0154 KMnO4 solution to react 25 0 mL of 0 0208 M H C 04 solution 5H C O4 aq 2MnO4 6H aq a 13 5 mL c 33 8 mL 2Mn aq 10CO g 8H O 1 b 18 5 mL d 84 4 mL

1 Choose the most correct option A A sample of pure water whatever the source always contains by mass of oxygen and 11 1 by mass of hydrogen a 88 8 b 18 c 80 d 16 B Which of the following compounds can NOT demonstrate the law of multiple proportions a NO NO c H O H O C Which of the following temperature will read the same value on celsius and Fahrenheit scales a 40 b CO CO d Na S NaF b 40 c 80 d 20 D SI unit of the quantity electric current is a Volt c Candela E In the reaction N 3H 2NH the ratio by volume of N H and NH is 1 3 2 This illustrates the law of b Ampere d Newton a definite proportion b reciprocal proportion Exercises c multiple proportion d gaseous volumes a 4 5 c 0 25 F Which of the following has maximum number of molecules a 7 g N c 8 g 0 G How many g of H O are present in 0 25 mol of it b 2 g H d 20 g NO b 18 d 5 4 H The number of molecules in 22 4 cm of nitrogen gas at STP is a 6 022 x 1020 b 6 022 x 1023 c 22 4 x 1020 d 22 4 x 1023 I Which of the following has the largest number of atoms a 1g Au s b 1g Na s 2 Answer the following questions A State and explain Avogadro s B Point out the difference betwe carbon and 12 u of carbon C How many grams does an hydrogen weigh D Calculate the molecular ma following in u a NH b CH COOH c CH E How many particles are pre mole of a substance F What is the SI unit of amc substance G What is meant by molar vol gas H State and explain the law of com of mass I State the law of multiple propc 3 Give one example of each A homogeneous mixture B heterogeneous mixture C element 4 Solve problems D compound A What is the ratio of molecules of NH and 1 mole of HNO A B Calculate number of moles of E in 0 448 litre of hydrogen gas c Ans 0 C The mass of an atom of hyd 1 008 u What is the mass of 1 of hydrogen 18 144 u D Calculate the number of atom of the following Given Atom of I 127 u a 254 u of iodine I b 254 g of iodine I Ans 2 atoms 1 2044 x 10 E A student used a carbon pencil his homework The mass of th found to be 5 mg With the help calculate The

23 The volume of a gas expands by 0 25m at a constant pressure of 10 N m2 The work done is equal to 1 2 5 erg 3 250 eV 2 250 J 4 250 cal

A system changes its state irreversibly at 300 K in which it absorbs 300 cals of heat When the same change is carried out reversibly the amount of heat absorbed is 900 cals The change in entropy of the system is equal to A 1 cal K C 2 cal K 93 B 3 cals K D 1 5 cals K

252 The heat of combustion of CH is 400 KJ mol Calculate the heat released when 40 g of H O is formed upon combustion 1 444 4 KJ 2 888 8 KJ 3 444 4 KJ 4 888 8 KJ

7 What will be the pH of the solution if 0 01 moles of HCl is dissolved in a buffer solution containing 0 02 moles of propanoic acid K 1 34 x 10 5 and 0 0152 moles of salt at 25 log 0 173 1 3 11 0 76 2 4 11 3 5 11 4 6 11

reaction Initial moles are If a is the degree of dissociation and P is the total pressure then the partial pressure of PC13 is 1 2 3 4 b aa a b c ac a ad a b c ad a 1 a b c aa a b c aa b aa PC1 PC13 Cl a b C P atm P atm P atm P atm

2 g of base X requires 100 ml of 0 4 N acid fo complete neutralisation The equivalent weight c base is 1 50 3 5 2 100 4 150

Ke log RT 0 is true relationship for the log Kc following reaction 1 PCI PCI Cl 2 2502 0 250 3 3 N 3H 2NH 2 4 2 and 3 both CE0018 T a

1 An alkene obtained by the dehydration of an alcohol 4 on ozonolysis gives molecules of acetaldehyde for every molecule of alkene The alcohol 4 is a CH3CH CH OH c CH3CH CHCH OH b CH3CH OH d CH3CH CHCH3

5 Initial temperature of an ideal gas is 75 C At what temperature the sample of neon gas would be heated to double its pressure if the initial volume of gas is reduced by 15 a 319 C b 592 C c 128 C d 60 C

1 In which case is number of molecules of water maximum 2018 a 18 mL of water b 0 18 g of water c 10 mol of water

SOLUBILITY 27 Henry s law constant for dissolution of CH4 in benzene at 298 K is 2 x 105 mm of Hg Then solubility of CH4 in benzene at 298 K under 760 mm of Hg is 1 1 2 x 10 5 3 4 x 10 7 2 3 8 x 10 3 4 1 x 10

B 228 5 kJ mol C 114 25 kJ mol 1 D 114 25 kJ mol 2 31 Enthalpy of neutralization of H PO acid is 106 68 kJ mol using NaOH If enthalpy of neutralization of HCI by NaOH is 55 84 kJ mol Calculate AHjonization of H3PO3 into its ions A 50 84 kJ mol B 5 kJ mol C 2 5 kJ mol D 60 84 kJ mol 32 The lattice enthalnu of LLO

What is mass of sodium acetate CH3COONa required to make 200 ml of 0 245 molar aqueous solution Molar mass of CH3COONa 82 g mol NCERT Pg 23 1 3 g 3 5 0 2 4g 4 6 q

The reaction CaCO 1 of the high temperature 3 CaO is not dissociated CaO s CO2 g goes to completion in lime kiln because 2 CaO is more stable than CaCO3 4 CO escapes continuously

When CuSO4 reacts with Kl the oxidation number of changes by a 0 c 1 b 1 d 2

Electronegativity of the following elements increases in the order 1 C N Si P 3 Si P C N 2 N Si C P 4 P Si N C

The following sequence Atomic weight of Zn 2ZnS 30 2ZnO 2SO ZnO C Zn CO of reactions may be 65 S 32 How many tons of Zn can be obtained form 32 33 tons of ZnS assuming that the yield is 75 for each reaction A 5 B 100 C 16 2 D 16 4

A 25 watt bulb emits monochromatic yellow light of wavelength of 0 57 m Calculate the rate of emission of quanta per second

For the equilibrium NH4HS s NH3 g H S g the expression of K in terms of equilibrium pressure p is a Kp p b K p c K p 1 d Kp p

18 The distance between 4th and 3rd Bohr orbits of He is b 1 322 x 10 10 m c 1 851 x 10 10 m a 2 645 x 10 10 m Vors Cas None of these

Which of the following relation holds true for an equilibrium reaction if its reaction quotient Q 1 1 AG 0 2 AG 0 3 AG AGO 4 AG AG

26 By how much will the potential of half cell Cu 2 Cu change if the solution is diluted to 100 times at 298 K 1 Increases by 59 mV 2 Decreases by 59 mV 3 Increases by 29 5 mV 4 Decreases by 29 5 mV

30 The number of hydrogen ions in 10 ml of a solution with pH 13 is 1 1013 3 6 023 1010 2 6 023 x 108 4 6 023 1013

A short solenoid of radius a number of turns per unit length n and length L is kept coaxially inside a very long solenoid of radius b number of turns per unit length 1 What is the mutual inductance of the system a Monb n n L c Mona n n L b Mona n n L d Mob n n L

Which of the following rate law has an overall ord of 0 5 for reaction involving substances x y and z AIIMS 9 1 Rate K C C C X 2 Rate K C 0 5 C0 5 C 0 5 3 Rate K C 5 C C 4 Bata KICHC 161 2

What volume of 6 0 M H SO4 should be mixed with 10 L of 0 1 M H SO4 to make 20 0 L of 3 0 M H SO4 upor dilution to volume a 1 7 L c 8 3 L b 5 L d 10 0 L

In Bohr s stationary orbits a electrons do not move b electrons move emitting radiations c energy of the electron remains constant Yangular momentum of the electron is h 2 5 Jo vii

A nuclear explosion has taken place leading to increase in concentration of C14 in nearby areas C14 concentration is C in nearby areas and C in areas far away If the age of the fossil is determined to be T and T at the places respectively then A The age of the fossil will increase at the place where explosion has taken place and T T 1 C In 2 C B The age of the fossil will decrease at the place where explosion has taken place and T T In C 2 C C The age of fossil will be determined to be same T C T C D

17 An element having bcc geometry has atomic mass 50 Calculate the density of the unit cell if its edge length is 290 pm 1 6 81 g cm 3 13 62 g cm 2 3 40 g cm 4 1 23 q cm 3

C 1 2 The radius of which of the following orbit is same as that of the first Bohr s orbit of hydrogen atom A He n 2 C Li2 n 3 n ron Z B Li n 2 D Be n 2 2004 in configuration 1s it would have energy lower than that of the 2

Q 28 Assuming no change in volume calculate the minimum mass of NaCl necessary to dissolve 0 010 m AgCl in 100 L solution S 0 01 10 0 K AgCl 3 105 K AgCl 1 10 1 Ag Cs1 Ag 5 4 Ag 201 San B 2015 NO C 2x15 N Ag U X S C

2 108 atoms of carbon are arranged side by side Calculate the radius of carbon atom if the length of this arrangement is 2 4 cm

v 0 341 x 10 2 34 1 x 1010 or v 5 84 x 105 m s Q 2 10 Electromagnetic radiation of wavelength 242 nm is just sufficient to ionize the sodium atom Calculate the ionization energy of sodium in kJ mol or