JEE Main · 2025 · 24 Jan 2025 · Shift 2 · Solutions

The observed and normal masses of compound

MX_{2}

are 65.6 and 164 respectively. The percent degree of ionisation of

MX_{2}

is ____ %.
(Nearest integer)

Answer: 75

Solution

For

M X_{2} \to M^{2 +} + 2 X^{-}

, the van't Hoff factor equals the ratio of normal to observed molar mass:

i = \frac{normal molar mass}{observed molar mass} = \frac{164}{65.6} = 2.5

For dissociation into 3 particles with degree of ionization

α

i = 1 + (3 - 1) α = 1 + 2 α

2.5 = 1 + 2 α ⟹ α = 0.75

The percent degree of ionization of

M X_{2}

is 75%.

JEE Main · 2025 · 24 Jan 2025 · Shift 2 · Integer answer

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