Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Solutions question

2019 · 11 Jan · Shift 2 · Q19
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Chemistry
  4. /Solutions
  5. /2019 · 11 Jan · Shift 2 · Q19

Solutions question

2019 · 11 Jan · Shift 2 · Q19

JEE MainChemistrySolutionsMCQ+4 / −1
K2Hgl4K_2Hgl_4K2​Hgl4​ is 40% ionised in aqueous solution. The value of its van't Hoff factor (i) is:
  1. A
    1.6
  2. B
    2.2
  3. C
    2.0
  4. D
    1.8
View written solutionFree

Correct answer: D

  1. Identify the solute and its dissociation

    The compound is potassium tetraiodomercurate(II): K2HgI4K_2HgI_4K2​HgI4​

    On ionisation in water, it dissociates as: K2HgI4→2K++[HgI4]2−K_2HgI_4 \rightarrow 2K^+ + [HgI_4]^{2-}K2​HgI4​→2K++[HgI4​]2−

    So, 1 formula unit produces 3 ions in total.

  2. Use the van't Hoff factor formula

    If a solute dissociates into ν\nuν particles and degree of ionisation is α\alphaα, then i=1+(ν−1)αi = 1 + (\nu - 1)\alphai=1+(ν−1)α

    Here, ν=3,α=40%=0.4\nu = 3, \quad \alpha = 40\% = 0.4ν=3,α=40%=0.4

  3. Substitute the values

    i=1+(3−1)(0.4)i = 1 + (3-1)(0.4)i=1+(3−1)(0.4) i=1+2(0.4)i = 1 + 2(0.4)i=1+2(0.4) i=1+0.8i = 1 + 0.8i=1+0.8 i=1.8i = 1.8i=1.8

  4. Match with the options

    i=1.8i = 1.8i=1.8

    Therefore, the correct option is D.

  5. Compare with stored correct answer

    Stored correct answer: D

    Our derived answer: D

    So, they agree.

PreviousNext

More from Solutions

  • A solution is prepared by dissolving 0.6 g of urea (molar mass = 60 g mol–1) and 1.8 g of glucose (molar mass = 180 g mol–1) in 100 mL of water at 27oC. The osmotic pressure of the solution is : (R = 0.08206 L atm K–1 mol–1)2019 · MCQ
  • Freezing point of a 4% aqueous solution of X is equal to freezing point of 12% aqueous solution of Y. If molecular weight of X is A, then molecular weight of Y is -2019 · MCQ
  • Molecules of benzoic acid (C6​H5​COOH) dimerise in benzene. 'w' g of the acid dissolved in 30 g of benzene shows a depression in freezing point equal to 2K. If the percentage association of the acid to form dimmer in the solution is 80,…2019 · MCQ
  • Two 5 molal solutions are prepared by dissolving a non-electrolyte non-volatile solute separately in the solvents X and Y. The molecular weights of the solvents are Mx and My, respectively where Mx = 43​ My. The relative lowering…2018 · MCQ
  • The mass of a non-volatile, non-electrolyte solute (molar mass = 50 g mol-1 ) needed to be dissolved in 114 g octane to reduce its vapour pressure to 75%, is :2018 · MCQ
  • For 1 molal aqueous solution of the following compounds, which one will show the highest freezing point?2018 · MCQ
  • 5 g of Na2​SO4​ was dissolved in x g of H2​O. The change in freezing point was found to be 3.82oC. If Na2​SO4​ is 81.5% ionised, the value of x (Kf for water=1.86oC kg mol−1) is approximately : (molar mass of S = 32 g mol−1 and that…2017 · MCQ
  • A solution is prepared by mixing 8.5 g of CH2​Cl2​ and 11.95 g of CHCl3​ . If vapour pressure of CH2​Cl2​ and CHCl3​ at 298 K are 415 and 200 mmHg respectively, the mole fraction of CHCl3​ in vapour form is : (Molar mass of Cl =…2017 · MCQ