The observed molar mass and normal molar mass of the compound MX 2 are 65.6 and 164 respectively. Find the percent degree of ionisation of MX 2 . ( Nearest \;integer )

Chemistry · Some Basic Concepts of Chemistry (Mole Concept) + Stoichiometry

JEE Main 2025 — 24 January, Evening Shift — Question 42

The observed molar mass and normal molar mass of the compound $\mathrm{MX_2}$ are $65.6$ and $164$ respectively.

Find the percent degree of ionisation of $\mathrm{MX_2}$ . $\quad (\text{Nearest \;integer})$

Numerical answer — enter this value.

\mathrm{MX_2 \rightarrow M^{2+} + 2X^-}

\text{Total\;particles \;after \;ionisation} = 3

Let degree of ionisation $= \alpha$

M_{\text{observed}} = \frac{M_{\text{normal}}}{1 + 2\alpha}

65.6 = \frac{164}{1 + 2\alpha}

1 + 2\alpha = \frac{164}{65.6} = 2.5

2\alpha = 1.5

\alpha = 0.75

\text{Percent\; degree \;of\; ionisation} = 75\%

Thus, the correct value is 75.

Answer key and solution verified before publishing.

Start with this question, then two more from the same chapter — with a tutor that explains every step. Free.