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ISC Class 12 Solutions — practice questions — page 2

Explore 50 free Solutions questions in ISC Class 12 Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

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Solutions questions and exercises with answers

Showing questions 31–50 of 50.

Tap every statement true of molalityRead the answer and worked solution →The van't Hoff factor (i) for sodium chloride (NaCl) in water is approximately:Read the answer and worked solution →For an ideal solution containing two volatile liquids A and B, Raoult's law gives the total vapour pressure as:Read the answer and worked solution →Osmotic pressure of a dilute solution is expressed by van't Hoff's equation as:Read the answer and worked solution →Flip and pair: measure with its denominatorRead the answer and worked solution →The MOLARITY of a solution containing 58.5 g NaCl dissolved in 1 L of solution is:Read the answer and worked solution →Complete the two concentration definitionsRead the answer and worked solution →Naming the measureRead the answer and worked solution →True or false: colligative propertiesRead the answer and worked solution →Assertion and reasonRead the answer and worked solution →The mole fraction of urea ($M = 60\,\text{g/mol}$) in an aqueous solution containing $6\,\text{g}$ of urea in $180\,\text{g}$ of water is approximately:Read the answer and worked solution →If $\mathrm{NaCl}$ undergoes complete dissociation in water, the van't Hoff factor $i$ is:Read the answer and worked solution →Three of these are wrong. Find the one that holds.Read the answer and worked solution →Which of these is NOT a colligative property?Read the answer and worked solution →Spot the one that does not belongRead the answer and worked solution →Molarity or molality?Read the answer and worked solution →Desalination of sea water is best carried out by:Read the answer and worked solution →A MINIMUM-BOILING azeotrope arises from:Read the answer and worked solution →Two solutions are said to be **isotonic** if they:Read the answer and worked solution →NEET · Chemistry · Colligative PropertiesRead the answer and worked solution →

Worked practice questions

Tap every statement true of molality

Read exercise and reference answers
Questions
  1. Items
    1. Text
      Divides by mass of solvent
      Matches the category
      Yes
    2. Text
      Unaffected by temperature
      Matches the category
      Yes
    3. Text
      Written with a small m
      Matches the category
      Yes
    4. Text
      Divides by volume of solution
      Matches the category
      No
    5. Text
      Changes when the solution is warmed
      Matches the category
      No
    Category
    True of MOLALITY
Mass-based, so temperature-independent. Source: syllabus Chemistry, Ch 1 Solutions.

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The van't Hoff factor (i) for sodium chloride (NaCl) in water is approximately:

  1. $1$ (no dissociation)
  2. $3$ (full dissociation into 3 ions)
  3. $0.5$ (association)
  4. $2$ (Na+ + Cl-)
Show answer and solution

Correct answer: D. $2$ (Na+ + Cl-)

NaCl dissociates almost completely in water into Na+ + Cl-, producing 2 particles per formula unit. So i ≈ 2 (theoretically 2; actual slightly less due to ion pairing). For non-electrolytes (glucose) i = 1. For CaCl2 (gives 3 ions) i = 3.

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For an ideal solution containing two volatile liquids A and B, Raoult's law gives the total vapour pressure as:

  1. $p_T = p_A^\circ p_B^\circ$
  2. $p_T = p_A^\circ \chi_B + p_B^\circ \chi_A$
  3. $p_T = p_A^\circ + p_B^\circ$
  4. $p_T = p_A^\circ \chi_A + p_B^\circ \chi_B$
Show answer and solution

Correct answer: D. $p_T = p_A^\circ \chi_A + p_B^\circ \chi_B$

**Raoult's law for an ideal solution:** each component's partial pressure equals its mole fraction in the solution times the vapour pressure of the pure component, $p_i = p_i^\circ \chi_i$. By Dalton's law the total is $p_T = p_A^\circ \chi_A + p_B^\circ \chi_B$.

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