In 10^–4 M K₂SO₄ solution, there are 10^–4 moles of potassium sulphate.
K₂SO₄ molecule contains 3 ions (2K⁺ and 1So₄^2–)
1 mole of K₂SO₄ contains 3 x 6.023 x 10²³ ions
10^–4 mole of K₂SO ₄ contains 3 x 6.023 x 1023 x 10^–4 ions = 18.069 x 10¹⁹.

Molar mass of glycine = 1(N) + 5(H) + 2(C) + 2(O)
= 1(14) + 5(1) + 2(12) + 2(16)
= 14 + 5 + 24 + 32
= 75 g/mol
m = 7.5 g
Number of moles of glycine \( =\frac{\mathrm{m}}{\mathrm{M}} \)
\(=\frac{7.5}{75}=0.1 \mathrm{~mol}\)
Mass of solvent H₂O = 500 g
= 0.5 kg
molality = \({no.\ of\ moles\ of\ solute\over mass\ of\ solvent\ (in\ Kg)}\)
no. of moles of glycine = \({mass\ of\ glycine\over molar\ mass\ of\ glycine}\)
\(=\frac{0.1}{0.5}=0.2 \mathrm{~m}\)

i) Molal depression constant:
Molal freezing point depression constant or Cryoscopic constant is defined as the depression in freezing point for 1 molol solution.
ii) It doesn't depend on the nature of the solute but depends on the nature of the solvent.
Example : K_f for water = 1.86 K kg mol^-1
K_f for benzene = 5.12 K kg mol^-1

Two solutions having same osmotic pressure at a given temperature are called isotonic solutions.

Generally the change in pressure does not have any significant effect in the solubility of solids and liquids as they are not compressible. However, the solubility of gases generally increases with increase of pressure.
Consider a saturated solution of a gaseous solute dissolved in a liquid solvent in a closed container. In such a system, the following equilibrium exists.
Gas (in gaseous state) = Gas (in solution)
According to Le-Chatelier principle, the increase in pressure will shift the equilibrium in the direction which will reduce the p.ressure. Therefore, more number of gaseous molecules dissolves in the solvent and the solubility increases.