Which of the following substances has the hig | vedclass

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(C) $MgO$ has the highest melting point due to its significantly higher lattice energy.All these compounds possess a similar $FCC$ (rock salt) crystal

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$MgO$

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(C) $MgO$ has the highest melting point due to its significantly higher lattice energy.All these compounds possess a similar $FCC$ (rock salt) crystal structure.Lattice energy is directly proportional to the product of the charges of the ions $(Z^{+} \cdot Z^{-})$. For $MgO$,the charges are $+2$ and $-2$,whereas for $NaCl$ and $KCl$,the charges are $+1$ and $-1$. Thus,the lattice energy of $MgO$ is much higher.Comparing $MgO$ and $BaO$,both have $+2$ and $-2$ charges,but $Mg^{2+}$ is smaller than $Ba^{2+}$. Since lattice energy is inversely proportional to the interionic distance $(r)$,the smaller size of $Mg^{2+}$ results in a shorter bond length and higher lattice energy for $MgO$ compared to $BaO$.Therefore,$MgO$ has the highest melting point.

Which of the following substances has the highest melting point?

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