Vapour pressure of chloroform (CHCl₃) and dichloromethane (CH₂Cl₂) at 25^oC are 200 mmHg and 41.5 mmHg respectively, Vapour pressure of the solution obtained by mixing 25.5 g of CHCl₃ and 40 g of CH₂Cl₂ at the same temperature will be
(molecular mass of CHCl₃= 119.5 u and molecular mass of CH₂Cl₂ = 85 u)

• 173.9 mmHg

• 615.0 mmHg

• 347.9 mmHg

• 347.9 mmHg

The freezing point depression constant for water is -1 . 86^o C m^-1. If 5.00 g Na₂SO₄ is dissolved in 45.0 g H₂O, the freezing points is changed by -3.82^oC. Calculate the van't Hoff factor for Na₂SO₄.

• 2.63

• 3.11

• 0.381

• 0.381

The van't Hoff factor, i for a compound which undergoes dissociation in one solvent and association in other solvent is respectively.

• Less than one and less than one

• Greater than one and less than one

• Greater than one and greater than one

• Greater than one and greater than one

A 0.1  molal aqueous solution  of a weak  acid is 30%  ionised. if K_f for water is 1.86^oC/m, the freezing point of the solution will be 

• -18^oC

• -0.54^oC

• -0.36^oC

• -0.36^oC

200 mL of an aqueous solution of a protein contains its 1.26 g . The osmotic pressure of this solution at 300 K is found to be  2.57 x 10^-3 bar. The molar mass of protein will be (R = 0.083 L bar mol^-1 K^-1)

• 51022 g mol^-1

• 122044 g mol^-1

• 31011 g mol^-1

• 31011 g mol^-1

An aqueous solution is 1.00 molal in KI. Which change will cause the vapour pressure of the solution to increase?

• Addition of NaCl

• Addition of Na₂SO₄

• Addition of 1.00 molal KI

• Addition of 1.00 molal KI

A solution of sucrose (molar mass = 342 g mol^-1) has been prepared by dissolving 68.5 g of sucrose in 1000 g of water. The freezing point of the solution obtained will be (k_f for water = 1.86 K kg mol^-1)

• -0.372^o C

• -0.520^o C

• +0.372^o C

• +0.372^o C

25.3 g of sodium carbonate, Na₂CO₃ is dissolved in enough water to make 250 mL of solution. If sodium carbonate dissociates completely molar concentration of sodium ion, Na⁺ and carbonate ion, CO₃^2- are respectively (Molar mass of Na₂CO₃ = 106 g mol^-1)

• 0.955 M and 1.910 M

• 1.910 M and 0.955 M 

• 1.90 M and 1.910 M 

• 1.90 M and 1.910 M 

What is the [OH^-] in the final solution prepared by mixing 20.0 mL of 0.50 M HCl with 30.0mL of 0.10 Ba(OH)₂?

• 0.10 M

• 0.40 M

• 0.0050 M

• 0.0050 M

A 0.0020 m aqueous solution  of an ionic compound Co(NH₃)₅(NO₂)Cl freezes at -0.00732^o C . Number of moles of ions which 1 mol of ionic compound produces on being dissolved in water will be (k_f = - 1.86^o C/m)

• 2

• 3

• 4

• 4