Q: 5 moles of liquid X and 10 moles of liquid Y make a solution having a vapour pressure of 70 torr. The vapour pressures of pure X and Y are 63 torr and 78 torr respectively. Which of the following is t

array cc X & Y \\ n_x=5 & n_y=10 \\ P_x^0=63 & P_y^0=78 array aligned & aligned & P_ s( calc.) =P_x^0 x_x+P_y^0 X_y \\ & = 63 5 15 +78 10 15 \\ & =21+52 \\ & =73 \\ & P_ s (obs.) =70 \\ & P_ s (obs.) P_ s (calc.) aligned \\ & -ve deviation aligned

Question 1

Consider the following statements about the solutions formed by mixing two liquids. A. An ideal solution thus formed obeys Raoult's law throughout the composition range. B. Mixture of chloroform and a

Accepted Answer

Statement A is correct as an ideal solution is defined as one that obeys Raoult's law over the entire range of concentration. Statement B is correct because in a mixture of chloroform and acetone, intermolecular hydrogen bonding occurs between the two different molecules. This makes the A-B interactions stronger than the A-A and B-B interactions in the pure liquids, resulting in a lower vapour pressure and a negative deviation from Raoult's law. Statement C is incorrect because a mixture of anil

Question 2

Mixture of chloroform and acetone forms a solution with negative deviation from Raoult's law due to :

Accepted Answer

Chloroform (CHCl_3) and acetone (CH_3COCH_3) form a non-ideal solution showing a negative deviation from Raoult's law. This is because the hydrogen atom of chloroform forms a hydrogen bond with the oxygen atom of acetone. The formation of this intermolecular hydrogen bond makes the attractive forces between the unlike molecules stronger than the attractive forces between the like molecules. As a result, the escaping tendency of the molecules from the liquid phase decreases, leading to a lower va

Question 3

Identify the correct statements : A. The molality of 2.5 g of ethanoic acid (Molar mass : 60 g mol^ -1 ) in 75 g of benzene solution is 0.556 m. B. The molarity of a solution containing 5 g of NaOH (m

Accepted Answer

Statement A : Molality is given by the number of moles of solute divided by the mass of solvent in kg. Moles of ethanoic acid = 2.5 60 = 1 24 mol Mass of benzene = 75 g = 0.075 kg Molality = 1/24 0.075 = 1000 24 75 = 1000 1800 = 5 9 = 0.556 m Statement A is correct. Statement B : Molarity is given by the number of moles of solute divided by the volume of solution in litres. Moles of NaOH = 5 40 = 1 8 mol Volume of solution = 450 mL = 0.45 L Molarity = 1/8 0.45 = 1000 8 450 = 1000 3600 = 5 18 = 0

Question 4

Assertion A : For an ideal solution formed by mixing liquids P and Q , _ mix H=0 and _ mix V=0 Reason R : No interactions occur between P and Q . In the light of the above statements, choose the most

Accepted Answer

For an ideal solution formed by mixing two liquids P and Q , the enthalpy of mixing ( _ mix H) and the volume of mixing ( _ mix V) are both zero. Thus, Assertion A is correct. In an ideal solution, the intermolecular attractive forces between the solute and solvent molecules ( P-Q interactions) are of the same magnitude as those between the pure components ( P-P and Q-Q interactions). It is incorrect to state that no interactions occur between P and Q . Thus, Reason R is not correct. Therefore,

Question 5

Match List - I with List - II array llll & array l List-I \ (Example) array & & array l List-II \ (Type of Solution) array \ A. & Humidity & I. & Solid in solid \ B. & Alloys & II. & Liquid in gas

Accepted Answer

A Humidity Liquid in Gas B Alloy Solid in solid C Amalgams Liquid in solid D Smoke Solid in Gas

Question 6

5 moles of liquid X and 10 moles of liquid Y make a solution having a vapour pressure of 70 torr. The vapour pressures of pure X and Y are 63 torr and 78 torr respectively. Which of the following is t

Accepted Answer

array cc X & Y \ n_x=5 & n_y=10 \ P_x^0=63 & P_y^0=78 array aligned & aligned & P_ s( calc.) =P_x^0 x_x+P_y^0 X_y \ & = 63 5 15 +78 10 15 \ & =21+52 \ & =73 \ & P_ s (obs.) =70 \ & P_ s (obs.) P_ s (calc.) aligned \ & -ve deviation aligned

Question 7

Which of the following aqueous solution will exhibit highest boiling point?

Accepted Answer

T _ b = i ~K _ b ~m - Consider m M - K _ b same for all i M (1) 1 0.01=0.01 (2) 2 0.01=0.02 (3) 3 0.01=0.03 (4) 1 0.015=0.015 iM ~T _ b ~T _ b

Question 8

The amount of glucose required to prepare 250 mL of M 20 aquepus solution is : (Molar mass of glucose : 180 ~g ~mol ^ -1 )

Accepted Answer

Molarity, M = w _2 1000 M _2 ( V ) w _2= Amount of glucose Given molarity = M 20 1 20 = w_2 1000 180 250 w_2= 180 250 20 1000 =2.25 ~g

Question 9

Mass of glucose ( C _6 H _ 12 O _6 ) required to be dissolved to prepare one litre of its solution which is isotonic with 15 ~g ~L ^ -1 solution of urea ( NH _3 CONH _2 ) is (Given: Molar mass in g mo

Accepted Answer

For isotonic solutions [osmotic pressure must be equal] _1= _2 C _1 RT = C _2 RT C _1= C _2 m 180 1 = 15 60 1 ( ~m is the mass of glucose) m= 180 4 =45 ~g

Question 10

The Henry's law constant ( K _H ) values of three gases ( A , B , C ) in water are 145,2 10^ -5 and 35 kbar , respectively. The solubility of these gases in water follow the order:

Accepted Answer

Value of Henry's law constant 1 Solubility of gas Higher the value of K _H at a given pressure, lower is the solubility of the gas in the liquid. K _H value of gases (given) : A C B Order of solubility of gases in water : B C A

Question 11

The plot of osmotic pressure ( ) vs concentration ( mol L ^ -1 ) for a solution gives a straight line with slope 25.73 L ^ bar mol-1 . The temperature at which the osmotic pressure measurement is done

Accepted Answer

= CRT Slope = RT aligned & 25.73=0.083 T \ & T = 25.73 0.083 =309.47 310 ~K aligned Temperature in ^ C =310-273 =37^ C

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