HSC Science (Electronics) 12th Standard Board Exam - Maharashtra State Board Important Questions

Write the formula to determine the molar mass of a solute using freezing point depresssion method.

The vapour pressure of pure benzene is 640mm og Hg. 2.175×10^-3kg of non-vloatile solute is added to 39 gram of benzene the vapour pressure of solution is 600mm of HG. Calculate molar mass of solute.

[C = 12, H = 1]

Why is molality of a solution independent of temperature?

The determination of molar mass from elevation in boiling point is called as

• cryoscopy
• colorimetry
• ebullioscopy
• spectroscopy

Colligative property depends only on ........................ in a solution.

1.0 x10^-3Kg of urea when dissolved in 0.0985 Kg of a solvent, decreases freezing point of the solvent by 0.211 k. 1.6x10 Kg of another non-electrolyte solute when dissolved in 0.086 Kg of the same solvent depresses the freezing point by 0.34 K. Calculate the molar mass of the another solute. (Given molar mass of urea = 60)

The substance ‘X’, when dissolved in solvent water gave molar mass corresponding to the molecular formula ‘X3’. The van’t Hoff factor (i) is _______.

(A) 3

(B) 0.33

(C) 1.3

(D) 1

A solution of glucose in water is labelled as 10% (W/W).

Calculate:

a. Molality

b. Molarity of the solution.

[Given: Density of solution is 1.20 g mL^-1 and molar mass of glucose is 180 g mol^-1 ]

The boiling point of water at high altitude is low. because________________ .

(a) the temperature is low.                                         

(b) the atmospheric pressure is low.

(c) the temperature is high.

(d) the atmospheric pressure is high

A solution containing 0.73 g of camphor (molar mass 152 g . mol^-1) in 36.8 g of acetone (boiling point 56.3°C) boils at 56.55°C. A solution of 0.564 g of unknown compound in the same weight of acetone boils at 56.46^oC. Calculate the molar mass of the unknown compound.

Define Cryoscopic constant.

Determine the osmotic pressure of a solution prepared by dissolving 2.5 × 10⁻² g of K₂SO₄ in 2L of water at 25°C, assuming that it is completely dissociated.

(R = 0.0821 L atm K⁻¹ mol⁻¹, Molar mass of K₂SO₄ = 174 g mol⁻¹)

Determine the osmotic pressure of a solution prepared by dissolving 2.5 × 10⁻² g of K₂SO₄ in 2L of water at 25°C, assuming that it is completely dissociated.

(R = 0.0821 L atm K⁻¹ mol⁻¹, Molar mass of K₂SO₄ = 174 g mol⁻¹)

Which of the following solutions shows maximum depression in freezing point?

(A) 0.5 M Li₂SQ₄

(B) 1 M NaCl

(C) 0.5 M A1₂(SO₄)₃

(D) 0.5 MBaC1₂

Calculate the mole fraction and molality of HNO₃ in solution contaning 12.2%HNO₃ (Given atomic mases:H=1, N=13,O=16)

Calculate the amount of CaCl₂ (van't Hoff factor i = 2.47) dissolved in 2.5 L solution so that its osmotic pressure at 300K is 0.75 atmosphere.

Given : Molar mass of CaCl₂ is 111g mol^-1

R=0.082 L.atm K^-1mol^-1

Explain, why do aquatic animals prefer to stay at lower level of water during summer?

Which of the following is not a colligative property?

Which of the following is not a colligative property?

Gas (A) is more soluble in water than Gas (B) at the same temperature. Which one of the two gases will have the higher value of KH (Henry’s constant) and why