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Chemistry Questions and Answers August 15, 2020

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Calculate the molal elevation constant of water evaporates at 100C with the absorption of 536 (R 2 cals) calories per gm (a) 0.519C (b) 0.0519C (c) 1.519C (d) 2.519C

0.15g of a substance dissolved in 15g of solvent boiled at a temperature higher by 0.216C than that of the pure solvent. Calculate the molecular weight of the substance. Molal elevation con stant for the solvent is 2.16C. (a) 216 (b) 100 (c) 178 (d) None of these

If latent heat of fusion of ice is 80 cals per g at 0C, calculate molal depression constant for water. (a) 18.63 (b) 186.3 (c) 1.863 (d) 0.1863

1 What weight of NaCl is added to one litre of water so that ATK 500 (a) 5.85 g (b) 0.585 g (c) 0.0585 g (d) 0.0855 g

Assuming each salt to be 90 dissociated, which of the following will have highest boiling point (a) Decimolar Al(SO4)3 (b) Decimolar BaCl (c) Decimolar NaSO4 (d) A solution obtained by mixing equal volumes of (b) and (c)

The Vant Hoff factor for a dilute aqueous solution of glucose is (a) zero (b) 1.0 (c) 1.5 (d) 2.0

The correct relationship between the boiling points of very dilute solution of AlCl3 (TK) and CaCl (TK) having the same molar concentration is (a) T T (b) T T (c) T T (d) T T

The vapour pressure of an aqueous solution is found to be 750 torr at certain temperature T. If T is the temperature at which pure water boils under atmospheric pressure and same solution show elevation in boiling point AT, 1.04 K, find the atmospheric pressure 0.52 K kg mol) (Kb (a) 777 (b) 779 (c) 782 (d) 746

The Vant Hoff factor for a dilute aqueous solution of glucose is (a) zero (b) 1.0 (c) 1.5 (d) 2.0

The vant Hoff factor (i) for an infinitely dilute solution of NaHSO4 is (a) 12 (b) 13 (c) 3 (d) 2

Which of the following aqueous solution will show maximum vapour pressure at 300 K (a) 1 M NaCl (d) 1 M CH011 (b) 1 M CaCl (c) 1 M AICI,

The vapour pressure of a solution of a nonvolatile electrolyte B in a solvent A is 95 of the vapour pressure of the solvent at the same temperature. If the molecular weight of the solvent is 0.3 times the molecular weight of solute, the weight ratio of the solvent and solute are (a) 0.15 (b) 5.7 (c) 0.2 (d) 4.0

0 If P and P are the vapour pressures of a solvent and its solution respectively and N and N are the mole fractions of the solvent and nonvolatile solute respectively, then correct relation is (a) P PON (d) P Po(NN) (b) PPN (c) PoPN

The vapour pressure of pure liquid A is 10 torr and at the same temperature when 1 g of B solid is dissolved in 20 g of A, its vapour pressure is reduced to 9.0 torr. If the molecular mass of A is 200 amu, then the molecular mass of B is (a) 100 amu (b) 90 amu (c) 75 amu (d) 120 amu

The vapour pressure of a dilute aqueous solution of glucose is 750 mm of mercury at 373 K. The mole fraction of solute is (a) 1 10 (b) 1 7.6 (c) 1 35 (d) 1 76

In a solute undergoes dimerisation and trimerisation, the minimum values of the vant Hoff factors are (a) 0.5 and 1.50 (b) 1.5 and 1.33 (c) 0.5 and 0.33 (d) 0.25 and 0.67

The correct relationship between the boiling points of very dilute solution of AlCl3 (TK) and CaCl (TK) having the same molar concentration is (a) T T (b) T T (c) T T (d) T T

37. Which of the aq. solution has the highest boiling point (a) 0.1 M KNO3 (b) 0.1 M Na3PO4 (c) 0.1 M BaCl (d) 0.1 M KSO4

Consider equimolal aqueous solutions of NaHSO4 and NaCl with AT and AT as their respective , boiling point elevations. The value of Lt will be m0 (a) 1 (b) 1.5 (c) 3.5 (d) 23

Elevation of boiling point of 1 molar aqueous glucose solution (density 1.2 gml) is (d) 0.98 K (a) K (b) 1.20 K (c) 1.02 K

The freezing point of equimolal aq. solution will be highest for (c) La(NO3)4 (a) C6H5NHCl (b) Ca(NO3) (d) C6H12O6

Which of the following has been arranged in the order of decreasing freezing point (a) 0.05 M KNO3 0.04 M BaCl 0.140 M sucrose 0.075 M CuSO4 (b) 0.04 M BaCl 0.140 M sucrose 0.075 M CuSO4 0.05 M KNO3 (c) 0.075 M CuSO4 0.140 M sucrose 0.04 M BaCl 0.05 M KNO3 (d) 0.075 M CuSO4 0.05 M KNO3 0.140 M sucrose 0.04 M BaCl2

A solution contains 0.1 M of acetamide in 1 litre of glacial acetic acid. When the solution is cooled, the first crystal that appeared at the freezing point contains the molecule of (a) acetamide only (b) acetic acid only (c) both acetamide and acetic acid (d) None

What will be the molecular weight of CaCl, determined in its aq. depression of freezing point (a) 111 (b) 111 (c) 111 solution experimentally from (d) data insufficient

Which has maximum osmotic pressure at temperature T (a) 100 mL of 1 M urea solution (b) 300 mL of 1 M glucose solution (c) mixture of 100 mL of 1 M urea solution and 300 mL of 1 M glucose solution (d) all are isotonic

FeCl, on reaction with KFe(CN), in aqueous solution gives blue colour. These are separated by a semipermeable membrane AB as shown. Due to osmosis there is 0.1 M K4Fe(CN)6 Side X B 0.01 M FeCl3 Side Y SPM (a) blue colour formation in side X. (b) blue colour formation in side Y. (c) blue colour formation in both of the sides X and Y. (d) no blue

214.2 gram of sugar syrup contains 34.2 gram of sugar. Calculate (i) molality of the solution and (ii) mole fraction of the sugar in the syrup (a) 0.555m, 0.0099 (b) 0.455m, 0.0110 (c) 0.355m, 0.0199 (d) None of these

Calculate the amount of oxalic acid (H2CO4. 2HO) required to obtain 250 ml of semimolar solution. (a) 15.75 g (b) 1.575 g (d) None (c) 157.5 g

The degree of dissociation of Ca(NO3)2 in dilute aqueous solution containing 7.0 g of salt per 100.0 g of water at 100C is 70. If the vapour pressure of water at 100C is 760 mm Hg, the vapour pressure of the solution is

Mcthyl alcohol and cthyl alcohol have vapour pressure cqual to 88.5 mm and 42.0 mm respectively at 45C. If 16.0 g of methanol and 46.0 g of ethanol are mixed at 45C, the mole fraction of methanol in the vapour is........(the mixture may be taken as ideal solution). (a) 0.467 (b) 0.502 (c) 0.513 (d) 0.556

The vapour pressure of benzene at 80C is lowered by 10 mm when 2.0 g of a nonvolatile substance is dissolved in 78 g of benzene. The vapour pressure of pure benzene at 80C is 750 mm. The molar mass of the nonvolatile substance is (a) 150 (b) 1050 (c) 1500 (d) 1550

Twenty grams of a substance were dissolved in 500 ml. of water and the osmotic pressure of the solution was found to be 600 mm of mercury at 15C. Determine the molecular weight of the substance. (a) 1120 (b) 1198 (c) 1200 (d) None of these

1kg of an aqueous solution of Sucrose is cooled and maintained at 4C. How much ice will be separated out if the molality of the solution is 0.75 K, (HO) 1.86 Kg molK. (a) 277.15 gm (b) 518.31 gm (c) 795.86 gm (d) 1256.5 gm

River water is found to contain 11.7 NaCl, 9.5 MgCl, and 8.4. NaHCO, by weight of solution. Calculate its normal boiling point assuming 90 ionization of NaCl, 70 ionization of MgCl, and 50 ionization of NaHCO3 (K for water 0.52) (a) 105.95 C (b) 5.94 C (c) 120.27 C (d) 20.27 C

Mole fraction of A vapours above the solution in mixture of A and B (X0.4) will be Given P 100 mm Hg and P 200 mm Hg (a) 0.4 (b) 0.8 (c) 0.25 (d) none of these

A mixture contains 1 mole of volatile liquid A (P100 mm Hg) and 3 moles of volatile liquid B (P 80 mm Hg). If solution behaves ideally, the total vapour pressure of the distillate is (a) 85 mm Hg (b) 85.88 mm Hg (c) 90 mm Hg (d) 92 mm Hg

A liquid mixture having composition corresponding to point z in the figure shown is subjected to distillation at constant pressure. Which of the following statement is correct about the process (a) The composition of distillate differs from the mixture (b) The boiling point goes on changing (c) The mixture has highest vapour pressure than for any

The vapour pressure of a saturated solution of sparingly soluble salt (XC13) was 17.20 mm Hg at 27C. If the vapour pressure of pure HO is 17.25 mm Hg at 300 K, what is the solubility of sparingly soluble salt XC13 in moleLitre. (a) 4.04 x 10 (b) 8.08 102 (c) 2.02 x 102 (d) 4.04 103

The following graph represents variation of boiling point with composition of liquid and vapours of binary liquid mixture. The graph is plotted at constant pressure. Which of the following statement(s) is incorrect. Here X Y stands for mole fraction in liquid and vapour phase respectively (a) Xbenzene 0.5 and Y (c) X 0.3 and Y. benzene toluene

The freezing point depression of a 0.1 M aq. solution of weak acid (HX) is 0.20C. What is the value of equilibrium constant for the reaction HX (aq) H (aq) X (aq) Given K, for water 1.8 kg mol K. Molality Molarity (b) 1.35 103 (a) 1.46x104 (c) 1.21 x 10 (d) 1.35 x 104

The following graph represents variation of vapour pressure with composition of liquid and vapours of binary liquid mixture. The graph is plotted at constant temperature. Which of the following statement(s) is correct. Here X Y stands for mole fraction in liquid and vapour phase respectively (a) XBYB Vapour Pressure 100 (b) XA 1 XAYB (d) XAYA

The degree of dissociation (a) of a weak electrolyte A, B, is related to vant Hoff factor (i) by the expression. (a) a i1 (x y 1) (b) a i1 x y 1 (c) a xy1 i1 (d) a xy1 i1

1. Give the structures of compounds A, B, C, D and E for the sequence (10 Cyclohexanol E (C12H 140 3) 0 A (C6H 100) D (C12H 1402) marks) (1) C6H 5M g Br (2) H 0 Hot K M NO 4 B (C12H 160) H 30 C (C12H14) x

K for water is 1.86 K kg mol. If you automobile radiator holds 1.0 kg of water, how many grams of ethylene glycol (CHO) must you add to get the freezing point of the solution lowered to2.8C (a) 39 g (b) 27 g (c) 72 g (d) 93 g

At a given temperature, total vapour pressure in Torr of a mixture of volatile components A and B is given by PTotal 120 75 XB hence, vapour pressure of pure A and B respectively (in Torr) are (b) 120, 195 (c) 120, 45 (a) 120, 75 (d) 75, 45

2. Heptane has 9 structurer isomers. (a) Write structures of all the nine acyclic structural isomers of heptane. (8 marks),(b) For which of the structures in (a) is stereoisomerism possible (2 marks),(c) For each structure in (c) write all the stereoisomers and label all those related as (i) Enantiomers. (8 marks),(ii) Diastereomers.,(iii) Meso

What is the mole ratio of benzene (PB 0 150 torr) and toluene (PT 0 the given solution has a vapour pressure of 120 torr (a) 71 (b) 73 (c) 81 50 torr) in vapour phase if (d) 78

3) a) what is number of atoms present in 2 moles of oxygen gas,b) What is number of molecules are present in 2 moles of oxygen gas,c) Calculate number of moles of atoms of oxygen presence in 1.3 mol of sulfuric acid (HSO4),d) How many moles are in 64 grams of oxygen gas,e) How many atoms are in 1 molecule of HO,f) How many grams are in 1.25 x 102

Two liquids A and B form ideal solution. At 300 K, the vapour pressure of a solution containing 1 mole of A and 3 molcs of B is 550 mm of Hg. At the same temp., if one more mole of B is added to this solution, the vapour pressure of the solution increases by 10 mm of Hg. What is the the v.p. of A B respectively in their pure states. (a) 400, 600

4) The amount of pheromone (C19H380) secreted by a female insect to attract males is about 1.0 x 102g. How many molecules are there in this quantity (Atomic masses are C12amu, H 1 amu, 0 16 amu)

5) In 3 moles of ethane (C2H6), calculate the following (i) Number of moles of carbon atoms. (ii) Number of moles of hydrogen atoms. Number of molecules of ethane. (iii)

6) What mass of K3PO4 is required to prepare 400mL solution that contains 6 x 102 K3PO4 particles per liter of solution (atomic masses are K39amu, P31amu 016amu)

7) How many atoms are in 0.551 g of potassium (K)

A solution containing 28 g of phosphorus in 315 g CS (b.p. 46.3C) boils at 47.98C. If K, for CS is 2.34 K kg mol. The formula of phosphorus is (at. mass of P 31). (d) P (a) P6 (b) P4 (c) P3

1.0 molal aqueous solution of an electrolyte AB, is 60 ionised. The boiling point of the solution at 1 atm is (K(H0) 0.52 K kg mol) (a) 274.76 K (b) 377 K (c) 376.4 K (d) 374.76 K

8) How many H atoms are in 72.5 g of C3H8O

The freezing point of aqueous solution containing 5 by mass urea, 1 by mass KCl and 10 by mass of glucose is (a) 290.2 K (d) 250 K (b) 285.5 K (c) 269.93 K

9) The mole (Avogadro number N) is defined as the number of atoms in exactly 12 grams of 2C, calculate the a) number of atoms in 2 g of C b) number of atoms in 5 g of C

A complex is represented as CoCl3.xNH3. Its 0.1 M aq. solution shows AT, 0.558C (Kf (HO) 1.86 mol K) and assume 100 ionization and coordination no. of Co(III) is six. What is the complex (a) Co(NH3)4ClCI (c) Co(NH3)3C13 (b) Co(NH3)6Cl3 (d) Co(NH3)5ClC1

11) Nitrogen is made up of two isotopes, 14N and 5N. Given the nitrogens atomic weight of 14.007, what is the percent abundance of each isotope

The amount of ice that will separate on cooling a solution containing 50 g of ethylene glycol in 200 g water to 9.3C is (Kf 1.86 K kg mol) (a) 38.71 g (b) 38.71 mg (c) 42 g (d) 42 mg

12) Rubidium (Rb) has two isotopes, one is 84.912Rb and the other one is 86.909 Rb. The atomic weight of Rb is 85.47. Calculate the relative abundances of the two isotopes

Osmotic pressure of blood is 7.40 atm at 27C. Number of moles of glucose to be used per L for an intravenous injection that is to have the same osmotic pressure as blood is (a) 0.3 (b) 0.2 (c) 0.1 (d) 0.4

Osmotic pressure of 30 solution of glucose is 1.20 atm and that of 3.42 solution of cane sugar is 2.5 atm. The osmotic pressure of the mixture containing equal volumes of the two solutions will be (a) 2.5 atm (b) 3.7 atm (c) 1.85 atm (d) 1.3 atm.

14) A sample of naturally occurring silicon consists Si28(amu27.9769), Si29(amu28.9765) and Si30(amu29.9738). If the atomic mass of silicon is 28.0855 and the natural abundance of Si29 is 4.67,,what are the natural abundance of Si28 and Si30

15) Pb has an average atomic mass of 207.19amu. The three major isotopes of Pb are Pb206(205.98amu) Pb207(206.98 amu) and Pb208(207.98 amu). If the isotopes of Pb207 and Pb208 are present in equal amounts, calculate the percentage abundance of Pb206, Pb207, Pb208

If 6 g of urea, 18 gm glucose 34.2 gm sucrose is dissolved to make 500 ml of a solution at 300 K, what is the osmotic pressure (a) 4.92 atm (b) 9.84 atm (c) 14.77 atm (d) 12.96 atm

Ba ions, CN Co2 ions form a water soluble complex with Ba2 ions as free cations for a 0.01 M sol. of this complex, osmotic pressure 0.984 atm degree of dissociation 75). Find the coordination no. of Co2 ion in this complex (T 300 K, R 0.082 L atm K mol) (a) 5 (b) 4 (c) 6 (d) 7

16) The atomic weight of naturally occurring neon is 20.18amu. Naturally occurring neon is composed of two isotopes Ne20 (19.99amu) i) ii) Ne22(21.99amu),Calculate the number of Ne22 atoms in 12.55g sample of naturally occurring neon

If 200 ml of 0.2 M BaCl solution is mixed with 500 ml of 0.1 M Na2SO4 solution. What is the osmotic pressure of resulting solution (temperature 25C) (a) 6.685 atm (b) 12.307 atm (c) 3.162 atm (d) 4.927 atm

18) Copper is made up of two isotopes, Cu63 (62.9296amu) and Cu65 (64.9278amu). Given coppers,atomic weight of 63.546, what is the percent abundance of each isotopes

The value of observed and calculated mole weight of silver nitrate are 92.64 and 170 respectively. The degree of dissociation is (a) 60 (b) 83.5 (c) 46.7 (d) 60.23

Among the following the solution which shows the highest osmotic pressure is (d) 0.05 M NaSO4 (a) 0.5 M NaCl (b) 0.10 M BaCl (c) 0.05 M FeCl3

28) The atomic numbers for the elements U, V, W, P, S, R and F are 33, 16, 54, 58, 72, 55 and 35 respectively. (a) Write the electronic structures of the all the elements given above (b) To which groups and periods of the Periodic Table do the elements U, W and F belong (c) To which periods of the Periodic Table do the elements S and R belong (d)

Acetone and carbon disulphide form binary liquid solution showing positive deviation from Raoult law. The normal boiling point (T) of pure acetone is less than that of pure CS. Pick out the incorrect statements among the following. (a) Boiling temperature of mixture is always less than boiling temperature of acetone. (b) Boiling temperature of

Which of the following solutions are isotonic with respect to 0.5 M NaCl solution having degree of dissociation 0.8. (a) 153.9 gm of Sucrose dissolved in 500 ml of solution. (b) 0.3 M aQ. NaSO4 solution undergoing 100 ionization (c) 1.8 ww aQ. NaOH solution undergoing 100 ionization. (d) 1.2 M benzoic acid in a solution of benzene where the

How does electron affinity differ from electronegativity?

As a gas (insoluble in liquid) is bubbled through a liquid, part of the liquid vaporises and these vapours are carried off with the gas. As a sample of dry nitrogen gas is bubbled through a liquid, it is found that under identical conditions of temperature and pressure, a definite volume of wet nitrogen gas weighs more than the equal volume of dry

i) Explain why nitrogen has higher first ionization energy than oxygen.

A Two liquids A and B form an ideal solution. The solution has a vapour pressure of 700 torr at 90 C. It is distilled till 23rd of the solution is collected as condensate. The composition of the condensate is X0.75 and that of the residue is X 0.3. If the vapour pressure of the residue at 90 is 600 torr, which of the following option is correct.

Which of the following can form hydrogen bonds with water? a) CH3OCH3 b) CH4 c) F2 d) HCOOH e) Na

In which case vant Hoff factor are equal (a) KC1, 50 ionised (c) FeCl3, 30 ionised (b) KSO4, 40 ionised (d) SnCl4, 20 ionised

identify the type of intermolecular force exist For each of the following compounds and arrange them from lowest boiling point to highest boiling point a) CH4 b) CH2F2 c) CF4 d) BaF2

For the given electrolyte A B, the degree of dissociation a can be given as i1 (b) i (1a) xa ya xy1 (a) a (c) a 1i 1xy (d) None

Which has the equal boiling point (a) 0.1 M NaSO4 (c) 0.1 M MgCl (b) 0.1 M C6H12O6 (glucose) (d) 0.1 MAI (NO3)3

Which of the following is correct for an ideal solution (a) Raoults law is obeyed for entire concentration range and temperatures (b) . 0 (c) V. 0 mix mix (d) AS 0 mix

Which of the following will form nonideal solution (a) CH5OH and water (c) CHCl3 and CH, COCH (b) HNO3 and water (d) C H and C HCH3

The diagram given below represents boiling point composition diagram of solution of component A and B, which isare incorrect among the following TA T(K) XB (a) The solution shows negative deviation (b) ABinteractions are stronger than AA and BB (c) The solution is ideal solution (d) The solution shows positive deviation. TB

Which of the following isare correct for an ideal binary solution of two volatile liquids (eg. benzene toluene) (a) Its vapour is always richer in the more volatile component (compared to the liquid). (b) The liquid will gradually become richer in the less volatile component if such a mixture is boiled (distilled). (c) The Pr (ie. the total

For chloroform and acetone or for a solution of chloroform and acetone if p, (observed (actual)) is compared with Ps (Theoretical (Raoult)) then which of the following isare true (a) p (actual) p (raoult) Limit (b) Xchloroform Limit Xacetone (c) (d) p acetone 0 (pa acetone Ps actual) 0 0 (pchloroform Ps (actual)) 0 p chloroform near room

In which of the following pairs of solutions will the values of the vant Hoff factor be the same (a) 0.05 M K4 Fe(CN)6 and 0.10 M FeSO4 (b) 0.10 M K4Fe(CN)6 and 0.05 M FeSO4 (NH4)2SO4. 6HO (c) 0.20 M NaCl and 0.10 M BaCl (d) 0.05 M FeSO4 (NH4)2SO4. 6HO and 0.02 M KC1. MgCl. 6HO

of KSO4 When 100 ml of 0.2M BaCl (aq) is added to 100ml of 0.2M KSO4 solution, solution is lowered. Assume 100 dissociation of soluble salts and 100 precipitation of insoluble ones. (a) Freezing point (b) Boiling point (c) Vapour pressure (d) Osmotic pressure

Which pair will show positive deviation from raoults law (a) Methanol and chloroform (c) Ethanol cyclohexane (b) Methanol and cyclo pentane (d) Toulene benzene

Select the incorrect statements (a) The freezing of water is an endothermic process (b) Addition of any substance to water lowers it freezing point (c) At freezing point or below it, the freezing of both solute and solvent occurs (d) In freezing, AS solvent

Study the following figure, and choose the incorrect option (s) 0.1 m NaCl 0.05 m BaCl, Spm (a) There will be no movement of any substance across the membrane (b) BaCl will flow towards the NaCl solution. (c) The osmotic pressure of 0.1 M NaCl is higher than the osmotic pressure of 0.05 M BaCl assuming complete dissociation of electrolyte (d) NaCl

The vapour pressure of two pure liquids, A and B that form an ideal solution are 300 and 800 torr respectively, at temperature T. A mixture of the vapour of A and B for which the mole fraction of A is 0.25 is slowly compressed at temperature T. Calculate (a) the composition of the first drop of the condensate,

On mixing, heptane and octane form an ideal solution, At 373 K, the vapour pressures of the two liquid components (heptane and octane) are 105 kPa and 45 kPa respectively. Vapour pressure of the solution obtained by mixing 25.0 g of heptane and 35 g of octane will be (molar mass of heptane 100 g mol and of octane 114 g mol)

The vapour pressure of pure liquid solvent A is 0.80 atm. When a nonvolatile substance B is added to the solvent its vapour pressure drops to 0.60 atm. What is the mole fraction of component B in the solution

Two liquids A and B form an ideal solution at temperature T. When the total vapour pressure above the solution is 400 torr, the mole fraction of A in the vapour phase is 0.40 and in the liquid phase 0.75. What are the vapour pressure of pure A and pure B at temperature T

What is the composition of the vapour which is in equilibrium at 30C with a benzenetoluene solution with a mole fraction of benzene of 0.40 With a mole fraction of benzene of 0.60 P119 torr and P 37 torr