In the given cooling curve,what is the crystallization temperature in $K$?

Among the following,the incorrect statement is:

The only $INCORRECT$ statement for cubic metallic crystal is

Which of the following statement(s) is (are) correct?

Give the correct order of initials $T$ (true) or $F$ (false) for the following statements:
$I.$ In an anti-fluorite structure,anions form $FCC$ lattice and cations occupy all tetrahedral voids.
$II.$ If the radius of cations and anions are $0.2 \ \mathring{A}$ and $0.95 \ \mathring{A}$,then the coordination number of the cation in the crystal is $4$.
$III.$ An atom/ion is transferred from a lattice site to an interstitial position in a Frenkel defect.
$IV.$ The density of a crystal always increases due to a substitutional impurity defect.

$A$ mixture of $KCl$ and $KF$ is added to sodium chloride.