Answer:
[tex]\huge\underline{\red{A}\blue{n}\pink{s}\purple{w}\orange{e}\green{r} -}[/tex]
The formula of Density for a random unit cell is as follows -
[tex]Density = \frac{ Z _{effective} \times M }{N _{a} \times a {}^{3} } \\ [/tex]
where ,
★ [tex]Z _{effective}[/tex] = number of atoms in a unit cell
★ M = molar mass
★ [tex] N _{a} = Avogadro's \: Number = 6 × 10^{23}[/tex]
★ a = edge length
now ,
In a tetragonal unit cell ,
the atoms are present over the corners as well as the at the body centre.
Therefore ,
[tex]Z _{effective} = contribution \: by \: the \: 8 \: corners \: + contribution \: by \: the \: body \: centre[/tex]
[tex]\implies \: (\frac{1}{8} \times 8) \: + \: 1 \\ \\ \implies \: 1 + 1 \\ \\ \implies2[/tex]
And ,
[tex]N _{a} = 6 \times 10 {}^{23} [/tex]
Substituting the values of the following in the formula of Density , we get
[tex]\bold\purple{Density = \frac{2 \times M}{6 \times 10 {}^{23} \times a {}^{3} }} \\[/tex]
hope helpful :D