Mixtures and Alligation Questions

Multiple choice
  1. Will remain unchanged in $A$ and $B$
  2. Will increase in $A$ and decrease in $B$
  3. Will decrease in $A$ and increase in $B$
  4. Will increase in both $A$ and $B$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to Dalton's Law or simply the nature of ideal gases, if the compartments are equal and the pressure is the same, removing the wall does not change the pressure because the total volume and total moles remain constant relative to the initial state.

Multiple choice
  1. $0.007$ atm
  2. $1.04$ atm
  3. $0.13$ atm
  4. $1.97$ atm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Dalton's Law of Partial Pressures states that the total pressure of a gas mixture is the sum of the partial pressures of its individual components. Total = 0.03 + 0.66 + 0.35 = 1.04 atm.

Multiple choice
  1. $\dfrac { RT }{ 50 }$
  2. $\dfrac { RT }{ 100 }$
  3. $\dfrac { RT }{ 10 }$
  4. $\dfrac { RT }{ 40 }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Gas A contributes 1.6/32 = 0.05 mol, and gas B contributes 2.2/44 = 0.05 mol, giving 0.10 mol in total. From PV = nRT with V = 10 dm^3, P = 0.10RT/10 = RT/100.

Multiple choice
  1. $111\space mm$
  2. $222\space mm$
  3. $333\space mm$
  4. $444\space mm$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Using Boyle's Law P1V1 = P2V2, the final pressure P = (P1V1 + P2V2) / V_total. P = (200 * 720 + 400 * 750) / 1000 = (144000 + 300000) / 1000 = 444000 / 1000 = 444 mm.

Multiple choice
  1. Half of $740\space mm$
  2. Unchanged

  3. $\displaystyle\frac{1}{9}th$ of $740\space mm$
  4. Double than $740\space mm$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to Dalton's Law of Partial Pressures, the total pressure is the sum of partial pressures. If the number of molecules is equal, the partial pressures are equal (740/2 = 370 mm each). Removing oxygen leaves only hydrogen, so the pressure becomes 370 mm, which is half of 740 mm.

Multiple choice
  1. $60$ $mm \:Hg$
  2. $80$ $mm \:Hg$
  3. $100$$mm \:Hg$
  4. $150$ $mm \:Hg$
  5. $200$ $mm \:Hg$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Neon initially occupies 300 mL at 100 mm Hg. After expansion into the combined 500 mL volume, its partial pressure is 100 × 300/500 = 60 mm Hg. The oxygen does not affect this calculation.

Multiple choice
  1. $0^\circ C$
  2. $10^\circ C$
  3. $-30^\circ C$
  4. $>10^\circ C$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Heat lost by water (5g, 30C to 0C) = 5 * 1 * 30 = 150 cal. Heat gained by ice (5g, -20C to 0C) = 5 * 0.5 * 20 = 50 cal. Remaining heat = 100 cal. This melts 100/80 = 1.25g of ice. Since not all ice melts, the final temperature is 0C.

Multiple choice
  1. 840 ml

  2. 420 ml

  3. 630 ml

  4. None of these

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Total moles of H2O2 = (0.1 * 0.1) + (0.4 * 0.5) = 0.01 + 0.2 = 0.21 moles. Reaction: 2KMnO4 + 5H2O2 + 6H+ -> 2Mn2+ + 5O2 + 8H2O. Moles of KMnO4 = (2/5) * moles of H2O2 = 0.4 * 0.21 = 0.084 moles. Volume of 0.1 M KMnO4 = 0.084 / 0.1 = 0.84 litres = 840 ml.

Multiple choice
  1. $10$%
  2. $15$%
  3. $20$%
  4. $25$%
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let initial moles be x (CO2) and y (CO). Total = x+y. Reaction: CO2 + C -> 2CO. If x moles of CO2 react, they produce 2x moles of CO. Net change in moles = +x. Increase = x / (x+y) = 0.20. x = 0.2x + 0.2y. 0.8x = 0.2y. y = 4x. Total = 5x. %CO2 = x/5x = 20%.