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Molar mass of a solute from the elevation of boiling point or depression of freezing point

This type of question, asked 3 times: 27 Jun 2022, 29 Jul 2022, 30 Jan 2023. All 3 questions below, oldest first.

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  1. Question 1

    27 Jun 2022

    145
    A solution containing 2.5×10−3 kg2.5 \times10^{- 3}\text{ }kg of a solute dissolved in 75×10−3 kg75 \times10^{- 3}\text{ }kg of water boils at 373.535 KK. The molar mass of the solute is gmol −1gmol\ ^{- 1}. [nearest integer] (Given: Kb(H2O)=0.52 KKgK_{b}\left( H_{2}O \right)= 0.52\text{ }KKg mol−1mol^{- 1}, boiling point of water =373.15 K= 373.15\text{ }K )

  2. Question 2

    29 Jul 2022

    143
    1.80 g1.80\text{ }g of solute A was dissolved in 62.5 cm362.5{\text{ }cm}^{3} of ethanol and freezing point of the solution was found to be 155.1 K155.1\text{ }K. The molar mass of solute AA is ____ g mol−1g{\text{ }mol}^{- 1}. [Given: Freezing point of ethanol is 156.0 K156.0\text{ }K. Density of ethanol is 0.80 g cm−30.80\text{ }g{\text{ }cm}^{- 3}. Freezing point depression constant of ethanol is 2.00 K kg mol−12.00\text{ }K\text{ }kg{\text{ }mol}^{- 1}]

  3. Question 3

    30 Jan 2023

    58
    A solution containing 2 g2\text{ }g of a non-volatile solute in 20 g20\text{ }g of water boils at 373.52 K373.52\text{ }K. The molecular mass of the solute______ is g mol−1g\ mol^{-1}. (Nearest integer) Given, water boils at 373 K373\text{ }K, KbK_b for water =0.52 K kg mol−1= 0.52\text{ }K\text{ }kg\text{ }mol^{-1}