Which of the following is true for the compound $AB$,if it is formed by the transfer of an electron from $A$ to $B$?

When metals combine with non-metals,the metal atom tends to:

The Born-Haber cycle for $KCl$ is evaluated with the following data:
$\Delta_{f} H^{\ominus}$ for $KCl = -436.7 \ kJ \ mol^{-1}$
$\Delta_{sub} H^{\ominus}$ for $K = 89.2 \ kJ \ mol^{-1}$
$\Delta_{ionization} H^{\ominus}$ for $K = 419.0 \ kJ \ mol^{-1}$
$\Delta_{electron \ gain} H^{\ominus}$ for $Cl_{(g)} = -348.6 \ kJ \ mol^{-1}$
$\Delta_{bond} H^{\ominus}$ for $Cl_2 = 243.0 \ kJ \ mol^{-1}$
The magnitude of lattice enthalpy of $KCl$ in $kJ \ mol^{-1}$ is ..... . (Nearest integer)

The melting point of $RbBr$ is $682\,^{\circ}C$ while that of $NaF$ is $988\,^{\circ}C$. The principal reason for this fact is

Two elements have electronegativities of $1.2$ and $3.0$. The bond formed between them would be:

Which of the following substances has the highest boiling point?