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An element crystallizes in a body-centred cubic $(BCC)$ structure with an edge length of $400 \ pm$. Calculate the interatomic distance in the crystal. Additionally, if an atom has a radius of $300 \ pm$ and crystallizes in a face-centred cubic $(FCC)$ lattice, calculate the distance between the nearest neighbours.

$A$ body-centred cubic $(BCC)$ element of density $10.3 \ g \ cm^{-3}$ has a cell edge of $314 \ pm$. Calculate the atomic mass of the element. Also, Lithium borohydride crystallizes in an orthorhombic system with four molecules per unit cell. The unit cell dimensions are $a = 6.8 \ \mathring{A}$, $b = 4.4 \ \mathring{A}$, and $c = 7.2 \ \mathring{A}$. If the molar mass is $21.76 \ g \ mol^{-1}$, calculate the density of the crystal.

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

What is the percent by mass of titanium in rutile,a mineral that contains titanium and oxygen,if the structure can be described as a closest-packed array of oxide ions,with titanium in one half of the octahedral holes? What is the oxidation number of titanium? $(Ti = 48, O = 16)$

Which of the following statements is correct?