Which one of the following statements is not correct?

Match the following:

List-$I$	List-$II$
$A$. $ABCABC...$ layers	$I$. $F$-centres
$B$. Thermodynamics defects	$II$. $X$-ray diffraction
$C$. $Farbenzenter$	$III$. Vacancy defects
$D$. $Debye-Scherrer$ method	$IV$. Semiconductors
	$V$. Silver

The halide of a metal $MX$ crystallizes in a $ccp$ structure ($NaCl$ type). If all the atoms situated at one of the tetrad axes are removed,what will be the simplest molecular formula of the halide?

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

Silver has an atomic radius of $144 \ pm$ and the density of silver is $10.6 \ g \ cm^{-3}$. Based on this information, identify the correct statement.

The cubic unit cell structure of a compound containing cation $M$ and anion $X$ is shown below. When compared to the anion,the cation has a smaller ionic radius. Choose the correct statement$(s)$:
$(A)$ The empirical formula of the compound is $MX$.
$(B)$ The cation $M$ and anion $X$ have different coordination geometries.
$(C)$ The ratio of $M-X$ bond length to the cubic unit cell edge length is $0.866$.
$(D)$ The ratio of the ionic radii of cation $M$ to anion $X$ is $0.414$.