A 0.0020 m aqueous solution of an ionic compound [Co(NH3)5(NO2)]Cl freezes at $$-$$ 0.00732oC. Number of moles of ions which 1 mol of ionic compound produces on being dissolved in water will be (Kf = $$-$$1.86oC/m)
A
3
B
4
C
1
D
2
Explanation
The number of moles of ions produced
by 1 mol of ionic compound = i
0.5 molal aqueous solution of a weak acid (HX) is 20% ionised. If Kf for water is 1.86 K kg mol$$-$$1, the lowering in freezing point of the solution is
Concentrated aqueous sulphuric acid is 98% H2SO4 by mass and has a density of 1.80 g mL$$-$$1. Volume of acid required to make one litre of 0.1 M H2SO4 solution is
$$ \Rightarrow $$ V = $${{0.2 \times 1000} \over {36}}$$ = 5.55 mL
4
AIPMT 2006
MCQ (Single Correct Answer)
1.00 g of a non-electrolyte solute (molar mass 250 g mol$$-$$1) was dissolved in 51.2 g of benzene. If the freezing point depression constant, Kf of benzene is 5.12 K kg mol$$-$$1, the freezing point of benzene will be lowered by
A
0.2 K
B
0.4 K
C
0.3 K
D
0.5 K
Explanation
Molality of non-electrolyte solute
= $${1 \over {250 \times 0.0512}}$$ = 0.0781 m
$$\Delta $$Tf = kf
m
= 5.12 × 0.0781 = 0.4 K
Questions Asked from Solutions
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