1. Moles of K2SO4 to be dissolved in 12 mol water to lower its vapour pressure by 10mmHg at a ttemperature at which vopour pressure of pure water is 50 mmHg

2.decrease in vapour pressure of solution containing 2 mol (Cu(NH3)3Cl)in 3 moles H2O is 0.50 howmany moles AgCl is formed on reaction with AgNO3

Due to paucity of time, we are solving one of your questions. Try solving the other yourself. In case you feel any difficult, please get back to us.

Let P be the vapour pressure of pure solvent
P' be the vapour pressure of solution
n be the number of moles of solute
N be the number of moles of water (solvent)
We know,
P-P'P=nn+N     1050=nn+12 n+12 = 5n       n = 12/4           =3

Hence 3 moles of K2SO4 should be dissolved.

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