JEE Main 2014 · 6 Apr · Shift 1 · Chemistry Q38

← JEE Main 2014 · 6 Apr · Shift 1

ChemistrySingle correct+4 / -1Question 38 of 90

Consider separate solutions of 0.500 M $\ce{C2H5OH(aq)}$ , 0.100 M $\ce{Mg3(PO4)2(aq)}$ , 0.250 M $\ce{KBr(aq)}$ and 0.125 M $\ce{Na3PO4(aq)}$ at 25°C. Which statement is true about these solutions, assuming all salts to be strong electrolytes ?

They all have the same osmotic pressure.

0.100 M

\ce{Mg3(PO4)2(aq)}

has the highest osmotic pressure.

0.125 M

\ce{Na3PO4(aq)}

has the highest osmotic pressure.

0.500 M

\ce{C2H5OH(aq)}

has the highest osmotic pressure.

Answer and worked solution

Official answer: A

Osmotic pressure is proportional to $iC$ :

ethanol: $1\times0.500=0.5$ ;
$\ce{Mg3(PO4)2}$ : $5\times0.100=0.5$ ;
KBr: $2\times0.250=0.5$ ;
$\ce{Na3PO4}$ : $4\times0.125=0.5$ .

They are all equal.

Topics:van't Hoff factor Colligative properties

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JEE Main 2014 · 6 Apr · Shift 1, Chemistry question 38